Engine: fixes #3318: Red Hat Repositories initial conversion

This commit contains initial changes to support the Red Hat Repositories
page in the UI.

It also has some changes for the 'old tupane' version of
providers/products/repos.  Although we'll be removing that in the
future, went ahead and updated the files since was in there anyway.
Engine: fixes #3314, 3317: Red Hat Subscriptions initial conversion
Merge pull request #3250 from bbuckingham/engine-redhat_hat_repos

Engine: fixes #3318: Red Hat Repositories initial conversion
Merge pull request #3249 from bbuckingham/engine-subscriptions

Engine: fixes #3314, 3317: Red Hat Subscriptions initial conversion