ofproto: Fix uninitialized rule in ofproto_get_vlan_usage().

Found by inspection.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
classifier: Get rid of cls_rule_move() and it's user.

This makes rule creation a bit more straight forward.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
classifier: Use a match instead of a cls_rule in cursors.

This marginally simplifies the code, and makes the API more intuitive.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
Change the classifier API.