packaging - added check on firewall-cmd support

Added a check for --permanet option support for firewall-cmd.
If it's not supported, firewalld will not be available as
firewall manager.

Moved firewalld to global scope, the import will not fail
also if firewalld is not installed on the system.

Change-Id: I64c441c7fde548a8b2798c9f63d59962ff6e51c3
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>