add support for google errorprone

[ispringer]

There are only docs for the standard Maven compiler plugin here:

http://errorprone.info/docs/installation

[ifedorenko]

agree it'd be nice to support errorprone. problem is, takari lifecycle works best with eclipse jdt compiler backend but last time I checked errorprone only worked with javac (implementation relied on javac internal classes).

not closing this issue, but don't plan any work unless somebody ported errorprone to work with eclipse jdt compiler.