Provision With Salt

**This is still a work in progress**

This breaks up the duty of the Fabric script to focus on deployment and uses the masterless salt-minion for the provisioning. This addresses #11, #18, #26, #27, #28. It removes the requirement of argyle. A few things that still need to be sorted out before this is merged:

- [x] Better documentation (related to #30)
- [x] Sort out the non-zero return value of `salt-call`
- [x] Fix `MEDIA_ROOT` and `STATIC_ROOT` settings along with Nginx configuration
- [x] Firewall #29 

Follow up issues include:

- SSL #31
- Gunicorn updates #20 and #24 
- pylibmc #15 
- Support multiple projects/environments on a single server #33