Base command class and 'rb post' command.

Review Request #3449 — Created Oct. 24, 2012 and submitted — Latest diff uploaded

Information

RBTools
api

Reviewers

This includes the beginnings of the new base class for rb commands,
and the rb post command.

'rb post' is meant to eventually replace post-review for the common
task of generating a diff and creating/updating a review request. It
has many of the extra options of post-review stripped out, to make
it more focused.

"rb <command>" now uses the new entry points, expecting subclasses
of ``Command``. If the command isn't found it will attempt to
execute "rb-<command>" on the system.
Local testing with git repositories. This review request was posted using 'rb post'