Add RHEL7 beta support

RHEL7 still in beta status, so it will require the FORCE option,
until the GA release.

The main notable difference from another RHEL family members, it does
not have the mysql alias for the mariadb.

Change-Id: Ic90bb6c3dd9447fc80453c3dc1adb22cdfc6226f
Merge "Add RHEL7 beta support"