Adds support for building puppet on RHEL7 via spec.
Add initial support for building in a RHEL 7 mock

Building in an x86_64 mock, since RHEL has not provided a 32-bit release.
Merge pull request #2298 from mckern/add-el7-to-stable

Apply the RHEL7 work and merge it into stable
Merge branch 'stable'

Conflicts:
	ext/build_defaults.yaml