opsys.py: make from_os_release support SUSE
opsys.py: make from_os_release support SUSE

Fixes: #47
Signed-off-by: Nathan Cutler <f9d8c66a4e898e67db786769b5b347b640e1a9a6@suse.com>

ktdreyer/teuthology,SUSE/teuthology,ceph/teuthology,dmick/teuthology,ktdreyer/teuthology,SUSE/teuthology,dmick/teuthology,dmick/teuthology,SUSE/teuthology,ceph/teuthology