Put files needing for provisioning into /srv/provision

[mikeschinkel]

Put files needing for provisioning into /srv/provision to have a standard place and to remove the .tar files from the /srv/sites directory.

Also, I'd like to figure out a way that we can get users to be able to easily add things to their own repo that would a influence a reprovision, such as files for adding sites to nginx. This idea of fuzzy thus far, so just thinking "out loud."