Centralize startup code, and execute in all contexts

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.
Merge pull request #690 from cpennington/one-time-startup

One time startup centralization