Update to Android worker.
Merge pull request #436 from square/jw/fix-travis-ci

Update to Android worker.
Use Types.isSameType for comparing TypeMirrors.

The documentation on TypeMirror.equals states "Semantic comparisons of type equality should instead use Types.isSameType(TypeMirror, TypeMirror). The results of t1.equals(t2) and Types.isSameType(t1, t2) may differ.".