We need to use the develop branch for salt for the time being

As of https://github.com/saltstack/salt/commit/d6ccbd38f9f917f01f0b0ddcbd32dc20d0a568e4#diff-29a8d4513061a20d02e36c542ea18e19, the handling of the root MySQL password meets our needs... I think.

This isn't yet available in our stable or testing packages yet for CentOS