(maint) Update RHEL7 mock stub to pull Puppet from EPEL

We haven't shipped Puppet for RHEL7 yet, but we need it for numerous
tests to pass. In the spirit of the chicken and the egg, we should
pull Puppet from EPEL until we ship our own Puppet package.
Merge pull request #58 from mckern/use_epel

(maint) Update RHEL7 mock stub to pull Puppet from EPEL
(maint) Add Puppet Labs modules to RHEL7 mock stub

Without these, we won't find our own packages or dependencies
Merge pull request #59 from mckern/use_epel

(maint) Add Puppet Labs modules to RHEL7 mock stub
(maint) Add rubygem-rgen to EPEL whitelist for RHEL7

Without this, puppet won't install from EPEL.
Merge pull request #60 from mckern/use_epel

(maint) Add rubygem-rgen to EPEL whitelist for RHEL7
(maint) Add redhat-release-everything to RHEL7 mock setup list

In RHEL7 beta, redhat-release is now redhat-release-everything and without
redhat-release-everything installed, facter doesn't quite work right.
Also, today we learned how to mix packages & group names in a single install
command. So, here's some instituional knowledge to save!
Merge pull request #61 from mckern/use_epel

(maint) Add redhat-release-everything to RHEL7 mock setup list
(maint) Reconcile changes from FOSS RHEL7 mockstub with PE RHEL7 mockstub

This will ensure we're using a consistently usable base when we try to
build RHEL7 PE packages.
(maint) Remove errant conditionals from RHEL7 PE mockstub
Merge pull request #62 from mckern/use_epel

(maint) Reconcile changes from FOSS RHEL7 mockstub with PE RHEL7 mockstubs
Add systemd to EL7 base mocks

In order to use all of the el7 systemd packaging macros, they must
be available in the build environment prior to the installation
of packages in BuildDepends. This adds the systemd package to the
base el7 mock configs
Merge pull request #64 from shrug/master

Add systemd to EL7 base mocks
(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
(maint) Add global cleanup option for mock stubs

Toggling the cleanup_on_failure option in our mock stubs will make it
easier to diagnose problems with builds by leaving failed builds
staged in their initialized mocks. By default, both options are true
(which is consistent with the defaults as shipped in mock).