enforce findbugs 2.0.3.

Since Gradle 2.1 findbugs now defaults to 3.0.0 which is
not compatible with Java6

Change-Id: I790350701be581cf1800f312eff1d4d4cbd8688b
enforce findbugs 2.0.3.
automerge: f480df6

* commit 'f480df60f8eade942b4d08f477b02b13d15c43dc':
  enforce findbugs 2.0.3.