Fixes to enable SSL

- Point to SSL version of Jquery CDN
- Enable Mezzanine SSL Middleware
- Set SSL_ENABLED to True, which will force URLS starting with
  '/account' and '/admin' to SSL

Refs #173, #140
Update repo
Move SSL_ENABLED so that it's set before base.py gets loaded
Setup SECURE_PROXY_SSL_HEADER
Django converts X-Forwarded-Proto to HTTP_X_FORWARDED_PROTO
Remove SSL_ENABLED from settings.py

SSL_ENABLED is an 'editable' Mezzanine setting, which means that
Mezzanine will get its value from the DB, ignoring anything in the
settings.py file. The correct way to set it is from the admin web
interface.
Merge pull request #178 from python/hotfix/enabling-ssl

Hotfix/enabling ssl