Integration test for createForwardingRule

Implementation on several integration tests for the createForwardingRule action. The test checks the following features:

- The switch model is populated by the action with the new forwarding rules after its execution.
- The forwardingCapability only understands "output" actions.

For testing the new functionality, the FloodlightProtocolSession needed to be edited. Therefore, a clientFactory has been included, creating the Floodlight client by default, but giving the opportunity to set a MockClient for testing purposes.