Fix style issues from manifest parser CR

No outer parens, use .format instead of %s. I didn't realize the
preference for .format was universal, but the heavy parens are all
on me.
Move BUILD definitions into traditional "top" directory

This has at least two possible issues:
  - in order to get the path to 'resource_dir' in
     android_resources target, I exposed :param address.
     Is there a better way?
  - Using rglobs to grab sources from src. I don't see a good
     way around this while not using a relative path for the
     AndroidManifest.

But it is working well enough, and I think this is much more
inituitive for the user. This is where they would "expect" to
find a configuration file for an Android build.
Update docsstrings with target definition changes