* upstream/master: (1547 commits)
  Add margin between buttons if both retry and cancel are present
  Add margin between labels; remove underline hover style on status button
  udpated JS based on feedback
  Use default cursor for table header of project files (!5165)
  Fix duplicated entry in changelog [ci skip]
  Improves left static sidebar behaviour
  Include default callback URL (OAuth)
  Cleanup feature proposal template
  Simplify regex for string-based multi-word label surrounded in quotes
  Revert "Merge branch '18193-developers-can-merge' into 'master'"
  Upgrade Rails from 4.2.6 to 4.2.7.
  some JS magic to fix empty URL bug
  formats my test properly
  Update CHANGELOG
  Doesn't match empty label references surrounded in quotes
  Fix markdown rendering for label references that contains `.`
  Fix markdown rendering for label references that begin with a digit
  Fix markdown rendering for consecutive label references
  Stub omniauth provider for GitLab
  Update CHANGELOG
  ...