Merge remote-tracking branch 'gitlab-ce/master'

* ce/master: (349 commits)
  Revert "Update GITLAB_SHELL_VERSION"
  Update GITLAB_SHELL_VERSION
  Add feature toggles through Flipper
  Add GitLab Resources to University
  Add Documentation for GIT_CHECKOUT variable
  Remove entry variable
  Ui improvements for count badges and permission badges
  Rename the other jobs
  Update jobs_spec for changes from builds_spec
  Introduce source to pipeline entity
  Update docs related to protected actions
  Add changelog for protected branches abilities fix
  Ask for an example project for bug reports
  Center loading spinner in issuable filters
  Fix chat commands specs related to protected actions
  Fix builds controller specs related to protected actions
  Fix pipeline retry specs related to protected actions
  Fix environment model specs related to protected actions
  Fix build factory specs related to protected actions
  Fix job play service specs related to protected actions
  ...