add gradle 3.0

This is necessary to build support library with android gradle
plugin 2.2. The tools has not moved to 3.0 yet but support
library needs tools 2.2+ for a bugfix but gradle 2.14 has
another bug that breaks support lib (which is fixed on gradle 3.0).

Change-Id: I24dfaa585314ba7981df7475cd1bfbda590e9a79