Co-author: Ned Batchelder <ned@edx.org>

Inspired by: http://eldarion.com/blog/2013/02/14/entry-point-hook-django-projects/
Moves startup code to lms.startup and cms.startup, and calls the startup
methods in wsgi.py and manage.py for both projects.

Update existing tests and provide new ones to test new paradigm.

Refactor new set_many and update XBlock version number.

Added self to authors.

Conflicts:
	AUTHORS
	CHANGELOG.rst

stores_state is now only used in a single test, in conjunction with
has_score. In practice, it's never the case that stores_state is false
when has_score is true, so we can delete stores_state entirely, and just
use has_score for the grading test.

Use the XBlock library as the base for XModule, so that we can incrementally rely on more and more of the XBlock api