Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Bump bazel version to 1.0.0
  Upgrade bazlets to latest stable-2.16 to build with 2.16.12 API
  Upgrade bazlets to latest stable-2.15 to build with 2.15.17 API

Change-Id: If60c5b7f43dfb1322531bf16b3727678174b592b