Merge branch 'stable-2.8'

* stable-2.8:
  Update replication plugin to latest revision
  Allow download schemes to support but not require authentication
  Don't mention label abbreviation in search documentation
  Don't mention Verified as a default label in search documentation
  Minor fixes in dev-plugin documentation
  Document how a plugin can force state update of UiAction

Change-Id: I9ba217e20291271bdb1ec6d579efe37f9efc91ba