Merge remote-tracking branch 'upstream/master' into 27762-add-default-artifacts-expiration

* upstream/master: (26 commits)
  Allow searching issues for strings containing colons
  Fix Spinach failure
  [ci skip] UX Guide: Add personas
  Reuse User#find_by_any_email on UserFormatter#find_by_email
  Use leading periods on UserFormatter#find_by_external_uid
  Add CHANGELOG entry
  Add a simple cache for Gitlab::GithubImport::Client#user
  GitHub Importer - Find users based on their email address
  Don't use potentially slow ForkService in spec
  Added support for Authentiq Back-Channel Logout
  Added documentation for permalinks to most recent build artifacts
  Unify issues search behavior by always filtering when ALL labels matches
  Update GitLab Pages to v0.3.1
  Document Timecop usage for time-sensitive tests
  Add process for requesting approval for licenses
  Rename karma job to rake karma
  Update positioning of nav scroll arrows
  Fix issue where files on a fork could not be edited
  Move tanuki to left of title; increase max-width of title
  Refactor project stats & last_commit CSS; left align main nav items
  ...