Remove gevent

No Python 3 support
Remove django-avatar
Make static files more configurable

Adds dj-static for option of serving static files from WSGI server.
Use Python3 compatible code for basic auth module
Use pylibmc from Git repository

Development code supports Python 3, package does not
Use Heroku repo env name for Git push
Updates all requirements to latest versions

Removes South.
Update the main README