Run pecan py33-scaffolds jobs on py3k-precise nodes.

Also, update the regex in the zuul functions to match
`gate-pecan-tox-scaffolds-33`. This will make the jobs register with gearman so
that zuul can run them.

Change-Id: Ia7d2ff6fd39b7034061f46042e019217857bcbd4
Merge "Run pecan py33-scaffolds jobs on py3k-precise nodes."