Merge branch 'stable-2.15'

* stable-2.15:
  Upgrade bazlets to latest stable-2.15 to build with 2.15.10 API
  Automatically format BUILD file with buildifier lint mode
  Upgrade bazlets to latest stable-2.15 to build with 2.15.9 API
  Upgrade bazlets to latest stable-2.15 to build with 2.15.8 API
  Upgrade bazlets to latest stable-2.14 to build with 2.14.18 API

Change-Id: Ie4a7f3351624506b753c305600fc4727f6a22d58