1044596: Don't match beta product tags for release

Change the release module to reuse RHELProductMatcher
so it doesn't incorrectly identify content as being
RHEL content, so we don't attempt to find release
listings for them.

Add a rhelproduct.py with some of the RHEL product
specific tag comparisions, and update release
and productid modules to use it.
Merge pull request #905 from candlepin/alikins/1044596_release_rhel_check

1044597: Don't match beta product tags for release