Add artifacts needed for Gradle 2.1

Change-Id: Iec2748e7609e82d3e8360682672403fceadfdfff
Merge "Add artifacts needed for Gradle 2.1" into idea133
add findbugs 3.0.0 and its dependencies.

Change-Id: I0e1da78d9f53d47e9731343eb97d0ba05940ec3f
Merge "add findbugs 3.0.0 and its dependencies." into idea133
Added builder-model (Android Gradle plug-in) v0.13.0 to prebuilts.

Change-Id: I7c3d20033f87152488212d71fdb2ab8a80aaf2d5
Merge "Added builder-model (Android Gradle plug-in) v0.13.0 to prebuilts." into idea133