Unify ovirt-release-fedora and ovirt-release-el6

- detect and configure repositories in %post
- updated build scripts conforming to the new structure
- cleaned up build scripts

Bug-Url: https://bugzilla.redhat.com/1053037
Change-Id: Ib6b1c775e7afe36ef146fcfc2b7fed37f054a0c5
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>