python: Start fixing some Python 3 issues.

This patch fixes just the Python 3 problems found by running:

  python3 setup.py install

There are still many other issues to be fixed, but this is a start.

Signed-off-by: Terry Wilson <twilson@redhat.com>
[russell@ovn.org resolved conflicts with current master]
Signed-off-by: Russell Bryant <russell@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>

python/ovs/ovsuuid.py

@@ -42,7 +42,7 @@ def from_json(json, symtab=None):
         if not uuidRE.match(s):
             raise error.Error("\"%s\" is not a valid UUID" % s, json)
         return uuid.UUID(s)
-    except error.Error, e:
+    except error.Error as e:
         if not symtab:
             raise e
         try: