Merge branch 'remove-obsolete-repos' into 'master'

Merge branch 'remove-obsolete-repos' into 'master'

Make rhsm_repos major version specific and delete obsoleted repos.

This should delete all the repos that have been obsoleted by rhel entitlements.  @kdreyer please double-check that I've removed the right ones or if there are others that we should remove.

Also, trying to activate rhel 7 repos on a rhel 6 node fails.  I've made rhsm_repos major version specific and added the rhel 6 repos we want to enable to fix that.