Add EE usage ping

This MR implements the EE usage ping as a sidekiq-cron async task as discussed in #380. Currently we report:

* Active user count
* Max historical active user count
* License data (e.g. licensee, add-ons, etc.)

Screenshot:

![image](/uploads/552f5445c0034b604c35c2783161cbc1/image.png)


See merge request !557

Update permissions links

From CE https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5247

See merge request !559

Fix conflicts for the "developers can merge" feature

- This feature was implemented for CE in gitlab-org/gitlab-ce!4892.
- It was reverted in CE-master because of merge conflicts with EE-master
- This MR fixes the conflicts. Once this is merged in, the feature can be reintroduced to CE-master

/cc @rymai @rspeicher 

See merge request !564

1. Fix typos, minor styling errors.

2. Use single quotes rather than double quotes in `user_access_spec`.

3. Test formatting.

- https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4892#note_12892160
- This is more consistent.

1. If they are a developer with "Developers can Merge" switched on.

- Only send a param for the currently changed checkbox.
- Have the controller use strong parameters correctly, so that the PATCH
  works as expected.

1. Don't use case statements for dispatch anymore. This leads to a lot
   of duplication, and makes the logic harder to follow.

2. Remove duplicated logic.

    - For example, the `can_push_to_branch?` exists, but we also have a
      different way of checking the same condition within `change_access_check`.

    - This kind of duplication is removed, and the `can_push_to_branch?`
      method is used in both places.

3. Move checks returning true/false to `UserAccess`.

    - All public methods in `GitAccess` now return an instance of
      `GitAccessStatus`. Previously, some methods would return
      true/false as well, which was confusing.

    - It makes sense for these kinds of checks to be at the level of a
      user, so the `UserAccess` class was repurposed for this. The prior
      `UserAccess.allowed?` classmethod is converted into an instance
      method.

    - All external uses of these checks have been migrated to use the
      `UserAccess` class

4. Move the "change_access_check" into a separate class.

    - Create the `GitAccess::ChangeAccessCheck` class to run these
      checks, which are quite substantial.

    - `ChangeAccessCheck` returns an instance of `GitAccessStatus` as
      well.

5. Break out the boolean logic in `ChangeAccessCheck` into `if/else`
   chains - this seems more readable.

6. I can understand that this might look like overkill for !4892, but I
   think this is a good opportunity to clean it up.

    - http://martinfowler.com/bliki/OpportunisticRefactoring.html

1. When a merge request is being merged, save the merge commit SHA in
   the `in_progress_merge_commit_sha` database column.

2. The `pre-receive` hook looks for any locked (in progress) merge
   request with `in_progress_merge_commit_sha` matching the `newrev` it
   is passed.

3. If it finds a matching MR, the merge is legitimate.

4. Update `git_access_spec` to test the behaviour we added here. Also
   refactored this spec a bit to make it easier to add more contexts / conditions.

- Cherry-picked from `mvestergaard:branch-protection-dev-merge`
- https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4220

Closes #380

Fix error in admin dashboard when Geo is enabled and current node is nil.

Fixes the error in Dashboard when Geo (#76) is enabled and `current_node` is `nil`
Same fix is also applied to `rake gitlab:env:info`.

This will fix #785

See merge request !561

Revert "Optimistic locking for Issue and Merge Requests"

The migration to add `lock_version` in !5146 to every issue and merge request takes too long on GitLab.com since it has to add a default value of 0 to every row. Unfortunately, Rails 4.2 doesn't work properly if the value is left as `nil`; anything using optimistic locking cannot be edited. 

This bug was fixed in Rails 5.0 via this commit: https://github.com/rails/rails/commit/13772bfa49325a8dc26410d2dcb555665a320f92. I suggest we revert this change for now, and when we upgrade to Rails 5.0 we can reintroduce this feature.

See merge request !5245

Update rubocop to 0.41.2

Adds a couple of cops to the TODO files, but I wanted [a specific cop](https://github.com/bbatsov/rubocop/pull/3135/files) which just had about 65 offences, so Ill do that later.

See merge request !4999

CE upstream



See merge request !562

Disable PostgreSQL statement timeout during migrations

Long-running migrations may take more than the timeout allowed by the database. Disable the session's statement timeout to ensure migrations don't get killed prematurely.

See merge request !5263

Fix issues last update timestamp not preserved after importing a project

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/19689 and https://gitlab.com/gitlab-org/gitlab-ce/issues/19792 (similar, but not the same)

Now `updated_at` should be the time from the original project.

See merge request !5253

Reduce padding on collapsed diff message

## What does this MR do?

Reduce the padding on the collapsed diff message so it takes up less space.

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

Collapsed diffs took up too much space before.

## Screenshots (if relevant)

Before:

![image](/uploads/62c6fe19439bc3bc91bde83df72e7004/image.png)

After:

![image](/uploads/ec89230065c37fc4022d949d1233a90d/image.png)

## Does this MR meet the acceptance criteria?

- ~~[CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added~~
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - ~~Added for this feature/bug~~
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5256

Changed collapsed assignee tooltip to users name

## What does this MR do?

- Changes the collapsed assignee tooltip the users name rather than the username
- Updates the tooltip after updating the assignee

## What are the relevant issue numbers?

Closes #19280, #19281

## Screenshots (if relevant)

![Screen_Shot_2016-06-28_at_17.55.52](/uploads/e6ccc1703f59966c978e731a841aabdc/Screen_Shot_2016-06-28_at_17.55.52.png)

See merge request !4976

navbar_icon was renamed to custom_icon

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4909 it's still using `navbar_icon` but now it's renamed to `custom_icon` in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5156

/cc @iamphill @smcgivern @annabeldunstone 

See merge request !5265

Address UI feedback for admin area

## What does this MR do?
Addresses @dzaporozhets's feedback for !4424

## Why was this MR needed?
!4424 was merged with some design issues which affected other areas of the app and broke consistency. This MR fixes that.

## What are the relevant issue numbers?
#3946 

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5190

permissions/permissions just links to user/permissions since
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5210

Update permissons links to new page

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5210 updated the location in the docs, but we link to this page a bunch in the app too.

See merge request !5247

https://gitlab.com/gitlab-org/gitlab-ce/commit/c57471ddb456c9640f6d77128e1fc56c7a5b35b2

navbar_icon was used in:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4909

Refresh branch cache after `git gc`

As discussed in !5160, we should refresh the branch name list after expiring to make sure we are in a good state and that we do not affect view performance (as much).


See merge request !5235