Use Python 3.x compatible except construct
Use Python 3.x compatible except construct

Per (proposed) Hacking check, use except x as y:
instead of x,y:, which works with any Python version >= 2.6

Change-Id: I6e52cedec5c694bccae10541b1964a8547d4ffd1

citrix-openstack-build/python-ceilometerclient,citrix-openstack-build/python-ceilometerclient