Merge branch 'stable-3.1' into stable-3.2

* stable-3.1:
  Upgrade bazlets to latest stable-3.1 to build with 3.1.7 API
  Upgrade bazlets to latest stable-3.0 to build with 3.0.11 API
  Remove the commented-out snapshot plugin api lines

Change-Id: Ia4e22cb35b1973feec358bdc75162e2d76f8abf9