Include the RHN plugin in RHEVH7

The RHN plugin should still be part of the default build.

Change-Id: Ib20d5e587c388f567e39238ade3bd6617d8ee561
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1095029
Signed-off-by: Ryan Barry <rbarry@redhat.com>