Improve test props usage
Merge pull request #208 from edrevo/improve-test-props

Improve test props usage
Introduce the Both[T] class
Use Both in CommitmentNotification
Use Both[T] for Deposits
Introduce MockMicroPaymentChannel
Fix timer cancellation

 * Make AkkaSpec and BitcoinjTest afterAll methods compatible to allow
   timer cancellation
 * Remove some dead code related with timers

This change fixes #189
Replace ProtoMicroPaymentChannel in BuyerMicroPaymentChannelActor
Merge pull request #205 from sortega/issues/41

Last preparations for replacing ProtoMicroPaymentChannel with MicroPaymentChannel
Add a next method to Step

This way we avoid duplication about final step detection from the rest
of the code
Use MicroPaymentChannel in SellerMicroPaymentChannelActor
Move deposit checks to its own class
Finally remove DefaultProtoMicroPaymentChannel
PR feedback
Merge pull request #209 from sortega/issues/41

Remove ProtoMicroPaymentChannel
Add interface for PeerActor
Add replace BlockchainActor with PeerActor in ExchangeActor
Add last offer querying to MicropaymentChannel actors
Add ExchangeTransactionBroadcastActor interface
Add scaladoc to exchange actor