GitLab

* master: (189 commits)
  Remove redundant callbacks
  (Part 1) Resolve "Recognise when a user is trying to validate a private SSH key"
  Fix auto_cancel_pending_pipelines check
  Resolve "2FA should not attempt to use U2F in unsupported browsers"
  Resolve "Change the BitBucket import page to indicate that its for BB Cloud only, not for on-prem BB"
  Resolve "Help users find our contributing page"
  Docs broken links
  Refactor issue boards and get the EE changes to CE
  [Rails5] Fix error on missed :authenticate_user callback
  Delete non-latest merge request diff files upon diffs reload
  Adds test to cover the fix in #45575
  Log push output on exception
  Update issue_board.md
  edit issue_board.md
  edits to issue_board.md
  Update gitlab_chart.md
  Add note about license management first run
  Remove top margin for bootstrap popover headers
  Bump sprockets to 3.7.2 to address CVE-2018-3760
  Bring changes from EE
  ...