Merge branch 'stable-3.0' into stable-3.1

* stable-3.0:
  Move plugin configuration to a separate file
  Upgrade bazlets to latest stable-3.0 to build with 3.0.12 API
  Upgrade bazlets to latest stable-2.16 to build with 2.16.22 API

Change-Id: Ie6d5079a3530a2adbe276f9d7399b0e8315cd882