Merge branch 'stable-3.0'

* stable-3.0:
  Upgrade bazlets to latest stable-3.0
  Upgrade bazlets to latest stable-2.16
  Upgrade bazlets to latest stable-2.15
  Bump required bazel version to 1.0.0rc2
  Upgrade bazlets to latest stable-2.14

Change-Id: Ibf0ba38838f0c67548e363b679182f8446d8295e