Merge branch 'stable-2.14' into stable-2.15

* stable-2.14:
  FileBasedWebSessionCacheCleaner: Make CleanupTask a static inner class
  Upgrade bazlets to latest stable-2.14 to build with 2.14.20 API

Change-Id: Idece19dd3883912b5d950b1b77e36e3689d18f6f