Merge branch 'stable-2.4'

* stable-2.4:
  Update Gerrit 2.4 ReleaseNotes
  Add a new permission to permit rebasing changes in the web UI
  Restrict rebase a change in web UI to change owner, submitter
  Update Gerrit 2.4 ReleaseNotes

Change-Id: I0a68801c59343bdc57b58e933dd85b33e40193ae
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>