Improve text of MR merge widget and manual merge modal

Modal with manual merge instructions:

![Screen_Shot_2015-08-08_at_21.30.23](https://gitlab.com/gitlab-org/gitlab-ce/uploads/2bffe42e9ad76afd02efbe5816027767/Screen_Shot_2015-08-08_at_21.30.23.png)

Archived:

![archived](https://gitlab.com/gitlab-org/gitlab-ce/uploads/e1efa1d54ce7ead8de6e88ca34095c09/archived.png)

WIP:

![wip](https://gitlab.com/gitlab-org/gitlab-ce/uploads/14a831458d0946722559ec643f91678c/wip.png)

Missing target branch:

![missing_branch](https://gitlab.com/gitlab-org/gitlab-ce/uploads/340083bbacbc234906e58cf76c586a9e/missing_branch.png)

Missing source branch:

![missing_branch_source](https://gitlab.com/gitlab-org/gitlab-ce/uploads/72f80ed58efed88b2bbcf403b55b1a01/missing_branch_source.png)

Nothing to merge:

![nothing](https://gitlab.com/gitlab-org/gitlab-ce/uploads/85b0d9da87acacd53cffd0df58d8eed4/nothing.png)

Checking ability to merge:

![check](https://gitlab.com/gitlab-org/gitlab-ce/uploads/32d75322e622025610c446e8ca7d892d/check.png)

Conflicts when allowed to merge:

![conflicts](https://gitlab.com/gitlab-org/gitlab-ce/uploads/23fdb2c60a27d873b3cc8a008203eb59/conflicts.png)

Conflicts when not allowed to merge:

![conflicts_not_allowed](https://gitlab.com/gitlab-org/gitlab-ce/uploads/113462a80fc65bf48b20dc0efd808363/conflicts_not_allowed.png)

Mergeable when allowed to merge:

![accept](https://gitlab.com/gitlab-org/gitlab-ce/uploads/1b3bb1a71df21728fe9318e7a083bfba/accept.png)

Mergeable when not allowed to merge:

![not_allowed](https://gitlab.com/gitlab-org/gitlab-ce/uploads/d38fa5c96f8f9d7223bb6bc7ad36f29d/not_allowed.png)

Merge in progress:

![locked](https://gitlab.com/gitlab-org/gitlab-ce/uploads/b60dcf5eb70e6032b0e8aac766018df3/locked.png)

Merge failed:

![failed_2](https://gitlab.com/gitlab-org/gitlab-ce/uploads/3713b9a10298183935b028b658271ac9/failed_2.png)

Merged:

![merged](https://gitlab.com/gitlab-org/gitlab-ce/uploads/7f68a48dd197a71351c9a80c59c8ecbe/merged.png)

Closed:

![closed](https://gitlab.com/gitlab-org/gitlab-ce/uploads/d5ce040449b7db943bd2fbfffb607a10/closed.png)

cc @dzaporozhets @rspeicher

See merge request !1120

Trigger post-receive hooks after commits are made by GitLab
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1127

Fix event cache

Fixes #2236.

See merge request !1128

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add dropzone upload progress

This MR adds upload progress in percents to dropzone.

![progress](https://gitlab.com/vernik91/gitlab-ce/uploads/9be251e4f3a99bc1d65435b1f001d021/progress.png)

I thought, it can be nice small enhancement :)

See merge request !1125

Add `data-[type]-id` attribute to reference links

This is to let us redact them later in another filter.

See merge request !1110

link to configured gravatar host on profile page

This MR updates the profile page to display the correct address for the configured gravatar service. Previously this always showed gravatar.com even if gravatar.com was not being used as the gravatar service.

See merge request !1093

Ui improvements

* revert of wrong patch
* spall margin change

Explanation with screenshots here - https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/579#note_1845510

See merge request !1117

Improve abuse report wording

Fix transparency for msapplication-tile image

See merge request !1122

Cache all events

Use CSS to determine if the current user needs to see "Congratulations! Tweet about it" by project creation events and "Create Merge Request" by push events.

Implemented as described here: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/911#note_1559710

Addresses #2054, in part.

cc @dzaporozhets 

See merge request !1103

[ci skip]

This is to let us redact them later in another filter.

See merge request !1077

Fix CHANGELOG entries to belong in the right version

Reorder entries that were improperly grouped (one fix mentioned in #1522).

See merge request !1118

This reverts commit ee0fc2c3.

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Show incompatible projects in Bitbucket import status

### What does this MR do?

This MR displays incompatible Bitbucket projects (e.g. SVN, hg) in the status table.

### Why was this MR needed?

Users are confused when they don't see projects show up. The import list should show incompatible projects as we do for Google Code to make it more obvious to the user what is happening. (See !586 and 9c76a6fa).

### Screenshot

![image](https://gitlab.com/gitlab-org/gitlab-ce/uploads/264b080114c809c4a3a79580594af8b2/image.png)

### What are the relevant issue numbers?

#1871

See merge request !1114

Improve merge requests

- [x] Fetch merge request refs by IID
- [x] Ability to fetch any merge request
- [x] Link commits and diffs in merge request to target project
- [x] Improve merge request UI and command line instructions
- [x] Check merge request widget loading test coverage double

See merge request !1115

Show who last edited a comment if it wasn't the original author

Fixes #1796.

The `updated_by` user is also tracked for issues and merge requests, but it isn't currently shown, because "edited by Person" would give the idea that Person edited the description, while most updates to those are assignee/milestone/labels, in which case who made that change is already visible in the comments.

See merge request !1075

See #1871

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add `Group#add_*` convenience methods

Encapsulates the logic for `Gitlab::Access::WHATEVER` levels.

See merge request !1111

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>