Add scenario for output to controller action from group's bucket

This scenario verifies that the controller correctly interprets
output to controller action invoked from a group's bucket.
(Motivated by #218).
Fix applying action list from a group's bucket

Sending a packet either to a controller or out a port is done while
applying an action list.
(Motivated by #218).
Fix clause order in of_controller_v4:scenario
Merge pull request #219 from FlowForwarding/output-to-controller-from-bucket

Fix applying action list from a group's bucket