Merge branch 'master' into refactor/ci-config-move-global-entries

* master: (352 commits)
  Display last commit of deleted branch in push events (!4699)
  add changelog
  add missing attribute to attr_encrypted so it is fully backwards-compatible
  Add "GitLab team members only" to diagram link
  doc: note that .gitattributes uses default branch
  use the conf lexer so we have highlighted comments
  first draft of docs
  support cgi style options, such as erb?parent=json
  move the path alias to a more appropriate location
  make #custom_language private
  appease rubocop
  add an alias for Snippet#path
  appease rubocop
  check the tag so that an instance will pass too
  fix the spec, using project.change_head
  Revert "bump the master sha for gitlab-test!9"
  bump the master sha for gitlab-test!9
  add custom highlighting via .gitattributes
  Rename Licenses API to License Templates API
  Check for conflict with wiki projects when creating a new project.
  ...