(RE-1648) Update EL 7 Mock Configs for RHEL 7 RC

This update reflects the changes to repo structure in the RHEL7
release cadidate that came out in 4/14. We're still using the
EL7 bandaid structure since the final repo paths aren't formalized
yet. This will be updated when the final paths are determined
(be they CentOS or RHEL 7).
Merge pull request #65 from mckern/maint/RE-1648

(RE-1648) Update EL 7 Mock Configs for RHEL 7 RC