Fix ordering causing mysql_grant to reapply.

Because arrays are ordered lists, Puppet compares the list of retrieved
privileges against the defined privilege list.  This causes it to
reapply privilege if the ordering differs.  We now forcibly order in
the type and the provider to make sure we never falsely reapply
privileges.
Merge pull request #332 from apenney/ordering

Fix ordering causing mysql_grant to reapply.