Merge branch 'stable-2.14' into stable-2.15

* stable-2.14:
  Update maven build to 2.14.20
  Remove Buck based build
  Update bazlets to latest stable-2.14
  Update bazlets to Gerrit API 2.14.20

Change-Id: I5a2034080f072a807b87a66692ea18b46535e3fd