Update Vagrant provisioning, start migration to Salt

This starts the migration to salt and brings the vagrant provisioning up to date. The salt config still lacks parity with the chef config for production servers, but it will still generate a functional RtD instance using vagrant. Continuing migration to salt will require more porting some older chef/fabric deployment steps.

What has changed:
* Bumped vm base image Ubuntu 10.04 -> 13.04 to match production
* Moved vagrantfile to standard root path (not necessary?)
* Adds database user/db setup as provision step
* Bootstraps pip 1.5+ and updates pip install to work with new version of pip
* Adds local_settings, this could stand to be tuned/changed
* Executes database operations for RtD after pip install
* Chef configuration still lives, but vagrant uses salt now

This will produce a working instance, but local_settings will need further tuning for the site to be fully functional after provisioning in vagrant