Trim instructions to match reality
Introduce Salt as the primary provisioner for the WSUWP Environment

Thanks to [Salty WordPress](https://github.com/humanmade/Salty-WordPress/) for the inspiration.
Start provisioning the webserver with Nginx
Use the latest CentOS RPM available for Nginx
Require nginx before requiring nginx be running

I haven't wrapped my mind around this yet, but it was possible that the service.running check happened before nginx had completed installing. By adding a self requirement, it causes things to slow down and wait for the completion of the nginx package installation. I think.
Begin adding MySQL to provisioning

Installs 5.1 by default in CentOS 6.4, so we need to figure out some kind of repo to use for all of this. Ideally we'd find one that provides the latest stables for PHP, MySQL, and Nginx.