Implement RemoveOFForwardingAction.

The action checks given flow exists in the switch before trying to delete it.
Update protocolSessionTest to use client with the new interface.
Change IOpenflowForwardingCapability REST signature to accept flowId in the path in removeOpenflowForwardingRule call.
Merge pull request #701 from isartcanyameres/feature/removeOFfwdRule

Implement RemoveOFForwardingAction.