Merge branch 'stable-2.6'

* stable-2.6:
  Always run acceptance tests
  Update plugin versions during release
  Ensure core plugins are bundled by Maven
  Revert "Run Documentation formatting in parallel"
  Always run acceptance tests when creating a release build
  Run Documentation formatting in parallel
  Always build all components of Gerrit
  Always include documention in the build

Conflicts:
	gerrit-gwtexpui/.gitignore
	pom.xml

Change-Id: I4834f9da6be51cf4dc26634caad0e08470e8cc42