Prevent LDAP group sync from removing a group's last owner

As discussed with Patricio in support request 3151

When setting up LDAP group sync, users can easily lock themselves out of their own group (cf. http://doc.gitlab.com/ee/integration/ldap.html#locking-yourself-out-of-your-own-group). The group may be left without any owner and requires intervention of the GitLab Administrators - a significant burden for a large deployment. In order to avoid this situation, this patch prevents the LDAP group sync from removing the last owner of a group, in the same way GitLab does not allow removing the last owner of a group via the Members page. This "last owner" is left in place until a new owner is nominated, the next sync after that will remove him/her.

See merge request !7

Show "Remove logo" buttons only when Appearance settings are persisted

This also adds the CarrierWave cache fields to the form as recommended by https://github.com/carrierwaveuploader/carrierwave#making-uploads-work-across-form-redisplays so that uploaded files aren't lost between form submits (i.e., when there are errors on the form).

See gitlab/gitlabhq#2356

See merge request !410

This also adds the CarrierWave cache fields to the form as recommended
by https://github.com/carrierwaveuploader/carrierwave#making-uploads-work-across-form-redisplays
so that uploaded files aren't lost between form submits (i.e., when
there are errors on the form).

Fixing name for "branded login page"

I think that it would be easier to find this document with the name "Changing the appearance of the login page". I added the change to the doc and to the link.

See merge request !408

update changelog for 7.11.4

See merge request !409

Enhance the LDAP group synchronization

The response of our company's LDAP for a group looks like this:
```
dn: <dn-of-the-selected-group>
cn: <name-of-the-selected-group>
submember: uid=<username-of-a-submember>
member: uid=<username-of-a-member>
```
So the current implementation of the LDAP group synchronization in GitLab can't find any registered user in such a group. This merge request will fix this.

This is a "copy" of this merge request https://gitlab.com/subscribers/gitlab-ee/merge_requests/27 that was in the wrong repository.

See merge request !1

- a group within our company LDAP contains members and submembers
  --> also the submember attributes need to be check for the LDAP group synchronization

- the member attribute of groups provided by our company LDAP contains only a the members
  userid prefixed by 'uid=' an not the full dn of the user
  --> the member attribute has to be checked also for this value

Render "Enterprise Edition" on help page with dark font.

Addresses internal issue https://dev.gitlab.org/gitlab/gitlab-ee/issues/284.

See merge request !3

Fix error when viewing merge request with a commit that includes "Closes #<issue id>".

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/488 was giving a 500 error, and the logs showed this was the error.

I'm not yet sure why project would be `nil` in this case, but that's another issue.

cc @rspeicher

See merge request !2

Fix leftover user checks for git_annex after refactoring

Fixes #291

See merge request !404

Added info about active users

Added a small definition for users in EE, based on Tweet
https://twitter.com/SeanSith/status/595386784760082432

See merge request !403

Validate maximum active user count up until license issue date.

Step 1 of #298

cc @sytse @job

See merge request !402

update download info

See merge request !398

CE to EE

Fixes gitlab/gitlabhq#2330

See merge request !396

Update installation/update guides for 7.11.

See merge request !397

Conflicts:
	app/views/help/index.html.haml
	lib/gitlab/git_access.rb
	public/500.html
	public/502.html

Fix push event.

Fixes issue with !653.

See merge request !663