Merge remote-tracking branch 'upstream/master' into gem/sm/bump-google-api-client-gem-from-0-8-6-to-0-13-6

* upstream/master: (130 commits)
  Handle error when fetching ref for MR with deleted source branch
  refactor emails service
  fix update service
  refactor users update service
  refactor keys controller
  refactor some controllers to make them EE friendly
  fix specs
  fix users update service
  update initializers
  refactor services to match EE signature
  Change recommended MySQL version to 5.6
  Clarify artifact download via the API only accepts branch or tag name for ref
  Clean merge_jid whenever necessary on the merge process
  Rolling back change to n+1 detection
  Breadcrumbs receives padding when double lined
  karma spec fixes
  Add EEP to headings
  Added some Gitaly docs to `docs/development`
  Check orientation of profile image
  Fixed missing namespaces on navigation translations
  ...