config refactor wip
merging from master
pep8 and comments
renmaing prod.py and setting more defaults
renaming to use underscores
Pin django-cas to hash
Move to github.txt and make editable
moving the convert_tokens function to a common file
Merge pull request #6096 from edx/jarv/config-refactor-wip

Jarv/config refactor wip
Merge pull request #6127 from mitocw/cg/pin_cas_client

Pin django-cas to hash
Revert "Jarv/config refactor wip"
Merge pull request #6181 from edx/revert-6096-jarv/config-refactor-wip

Revert "Jarv/config refactor wip"