The syndic service was depending upon itself, which caused the salt run
to fail. This commit fixes that by depending on the salt-master service
rather than the salt-syndic service. I also made it more general by
using IDs to specify the provider rather than the name, which is a bit
less reliable.
If you are installing Salt via git/pip, the formula will try to overwrite your
install with packaged versions. This setting makes it possible to avoid that.
