Merge branch 'stable-2.5'

* stable-2.5:
  Update versions of included core plugins for Gerrit 2.5 release
  Finalize release notes for Gerrit 2.5

Change-Id: Ia13b273aba31b5b6dd94e8d1df2443a4cedb7a2c
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>