Merge pull request #319 from sortega/improve_logging

Improve how transaction signatures are logged
Persist received refund signature
Persist commitment notifications
Persist handshake result
Send less peer handshakes

Don’t send a peer handshake after recovering when we know it is not
needed anymore. For example, if the handshake was completed there is no
point for this external communication.
Merge pull request #320 from sortega/issue/113_persistent_exchange

Make handshakes persistent
Use Step instead of Int on BaseChannelActor
Make BuyerMicroPaymentChannelActor state explicit

This is needed for the persistency strategy I want to implement
Make micropayment channel actors derive from PersistentActor

But not yet persist anything
Introduce a base class for buyer channel tests
Simplify BuyerMicroPaymentChannelActor

Remove a loan pattern that is not needed anymore.
Add packaging files for Windows platforms

Including a workaround described in `README.md` to include C++ runtime libs.
Merge pull request #322 from apoloval/task/cf-99

Add packaging files for Windows platforms
Extract BuyerChannel from BuyerMicroPaymentChannelActor

This class allow to have simpler logic in the actor.
Make buyer channel actor persistent
PR feedback
Merge pull request #323 from sortega/realidad_alternativa

Persisten buyer channel actor reloaded