Made PGD Cookbook compatible with PGD Dev Branch

Refs #9

- Replaced django_settings.py.erb with modified version of current prod
settings.py.
    > All 'secrets' from old django settings file are translated over
    to new settings file.
- Changed attributes/default.rb repo and revision to be the pgd repository
and development branch.
- Modified reipes/default.rb config_file path from /pgd/settings.py to
/settings.py