Install android_binary and android_resource target. Add example android app

Added pants.backend.codegen.targets.android_resources. Installed it into pants.
Added a BUILD file to src/android/example/res to make it a target  and added it to the source_root.
Updated any tests that required it.

Addresses (and hopefully fixes) issue opened last review. Testing Done section updated with this change.

Testing Done:
ci.sh success: http://pastebin.com/fWF7Uu7W

travis success: https://travis-ci.org/pantsbuild/pants/builds/28652096

Reviewed at https://rbcommons.com/s/twitter/r/591/