Merge branch 'stable-2.15'

* stable-2.15:
  bazlets: Replace native.git_repository with skylark rule
  Format all Bazel build files with buildifier
  Upgrade bazlets to latest stable-2.15 to build with 2.15.5 API
  Update bazlets to latest stable-2.14 to build with 2.14.15 API
  Update bazlets to latest stable-2.15 and build with released 2.15.4 API
  Format all Bazel build files with buildifier
  Update bazlets to latest stable-2.14 to build with 2.14.14 API
  Update bazlets to latest stable-2.14 to build with 2.14.13 API

Change-Id: I1ed45509ea65a63575c00b50a3ede2a17241ea6c