Merge branch 'stable-3.1'

* stable-3.1:
  Update bazlets to latest stable-3.1
  Update bazlets to latest stable-3.0
  Rename GWT examples to have -GWT suffix
  Update maven build to 2.16.13
  Update bazlets to latest stable-2.16
  Update maven build to 2.15.18
  Update maven build to 2.14.20
  Remove Buck based build
  Update bazlets to latest stable-2.15
  Update bazlets to latest stable-2.14
  Update bazlets to Gerrit API 2.14.20

Just did: 'git merge --log -X theirs stable-3.1'

Change-Id: Ic8af5c25324ea96290c6ca9ba871f69185a7f60f