The MySQL recipe was purging old MySQL* verions to make way for version
5.5 or above. After the initial run, this was ok, but subsequent runs of
chef-client would cause the newer 5.5+ packages to be removed along with
their dependents; one of which was Zenoss. This was fixed by instructing
the recipe to purge all packages < 5.5.

Added checksum values for the MySQL repo RPM and zenoss RPM.