Replacing the google apputils with docopt.

Breaking the grow CLI into separate, dedicated files to make it easier to update and read.
Clean up routes. Remove dead code. PageController -> RenderedController.
Use --browser instead of --open, make it the default, and update routes.py
Fixing the WSGI app to no longer use gflags.

Added a --debug flag to the run command that runs the server in debug mode.
Moving the `multiprocessing` to the sub commands to fix hanging commands.