Resubmit commitment TX to the broker until publication
Fix heisenbug by using self messages

Replace code changing actor state from a future onComplete and improve
unit test.
Merge pull request #179 from apoloval/task/ForwardThatDamnedMessages

Use message forwarding in `SellerMicropaymentChannel`
Merge pull request #178 from sortega/issue/30_handshake

Use MessageForwarder for the rest for message resubmits of HandshakeActor
Remove initialization message in HandshakeArbiterActor

The case clase is temporary kept but passed as a constructor argument,
thus avoiding an initial idle actor state.
Extract HandshakeArbiterActor logic to HandshakeArbiter

Extract the logic unrelated with timeout and messaging to a
HandshakeArbiter class. Take advantage of the opportunity to introduce
types to avoid long argument lists on actor initialization.
Replace TestProbe by MockGateway

This way we can introduce delegates without breaking the tests
Add an expect forward method to MockGateway

We need a new signature to wait for any message source
Make HandshakeArbiterActor resubmit order matches

The notifications are resubmitted until commitment or rejection is
communicated by the corresponding exchange part.
Merge pull request #180 from sortega/broker_resubmits

Make server resubmit order matches