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:

- [ ] Better documentation (related to #30)
- [ ] Sort out the non-zero return value of `salt-call`
- [ ] Determine if we want to support multiple projects/environments on a single server
- [ ] Fix `MEDIA_ROOT` and `STATIC_ROOT` settings along with Nginx configuration

Follow up issues include:

- Firewall #29 
- SSL #31
- Gunicorn updates #20 and #24 
- pylibmc #15