Merge branch 'rs-issue-2058' into 'master'

Add admin_merge_request ability to Developer level and up

This was necessary because this permission is checked dynamically by
`app/views/shared/issuable/_context` when on a Merge Request.

Closes #2058

See merge request !1037

app/models/ability.rb

@@ -140,12 +140,13 @@ class Ability
         :create_project_snippet,
         :update_issue,
         :admin_issue,
-        :admin_label,
+        :admin_label
       ]
     end
 
     def project_dev_rules
       project_report_rules + [
+        :admin_merge_request,
         :create_merge_request,
         :create_wiki,
         :push_code

doc/permissions/permissions.md

@@ -17,6 +17,7 @@ If a user is a GitLab administrator they receive all permissions.
 | Create code snippets                  |         | ✓          | ✓           | ✓        | ✓      |
 | Manage issue tracker                  |         | ✓          | ✓           | ✓        | ✓      |
 | Manage labels                         |         | ✓          | ✓           | ✓        | ✓      |
+| Manage merge requests                 |         |            | ✓           | ✓        | ✓      |
 | Create new merge request              |         |            | ✓           | ✓        | ✓      |
 | Create new branches                   |         |            | ✓           | ✓        | ✓      |
 | Push to non-protected branches        |         |            | ✓           | ✓        | ✓      |