Use Python 3.x compatible except construct

Use except x as y:, which works with any
Python version >= 2.6

Change-Id: Ibf0f9aa8fb9725c1c9c00558ec217db96301678f

cinder/scheduler/scheduler_options.py

@@ -76,7 +76,7 @@ class SchedulerOptions(object):
         """Decode the JSON file. Broken out for testing."""
         try:
             return json.load(handle)
-        except ValueError, e:
+        except ValueError as e:
             LOG.exception(_("Could not decode scheduler options: '%s'") % e)
             return {}