Basic restructuring of docs so that it:

1. Picks up Django settings.
2. Includes the root README.rst file into the docs.
3. Points to the new locations for our apps.
Update requirements to add useful dev packages not required for running tests or the core apps
A little doc pruning to remove empty subsections
Merge pull request #15 from edx/submissions_docs

Docs outline
Merge branch 'master' into sanchez/first_pass_at_basic_api

Conflicts:
	requirements/test.txt