The official F20 cloud image does not contains the firewalld,
there is nothing to restart, and it fails the installation.
The previous workaround change, assumed all is_fedoras has
a restartable firewalld without ensuring is it installed at all.
RHEL6 even does not have a firewalld.
Closes-bug: #1329102
Change-Id: I3d119ce48af81b30bf02b01c2cd386612ac6ef90