Dagger 2.10-rc1

• Release of dagger.android classes to simplify injection of Android core types
• By default, stop emitting "Prefer to run the dagger processor" warnings
• Allow component builders' build() methods to return a supertype of the component

This is our first release using bazel instead of mvn. We don't believe there will be any noticeable differences, but if you see anything surprising please report an issue.