Merge pull request #140 from sortega/task/158_connection

Do not wait for a successful connection to start the app
Add a `ServiceRegistryActor` to provide a service location facility

The `ServiceRegistryActor` may be used to register services provided by actors
so they can be located by other actors, implementing a dependency location
pattern.
Implement `ServiceRegistry` convenience class

A convenience way to consumer `ServiceRegistryActor`.
Remove payment processor initialization

No dependency must be injected in payment processor actors, so the
`Initialize` message is removed so the actor is immediately initialized upon
start.
Inject service registry in order submission actor hierarchy
Inject service registry in order/exchange actor hierarchy
Inject service registry in market info actor
Fix a heisenbug in `ServiceRegistryActor`

Altering actor state in timeout handler leads to a race condition. Fix it by
sending a self-message instead.
Merge pull request #139 from apoloval/task/164c

Provide a service registry facility to locate global services in the actor system
Consider the Bitcoin fees while blocking funds in the wallet
Merge pull request #141 from gotoalberto/task/176

Consider the Bitcoin fees while blocking funds in the wallet
Move events to the model module
Enrich CoinffeineConnectionStatus with broker information
Use CoinffeineConnectionStatus in CoinffeinePeerActor
Make ProtoMessageGateway to use CoinffeineConnectionStatus

Use it both for replying RetrieveConnectionStatus and to publish
connection status events as they happen. Rely on TomP2P listeners
to track active peer “connections” (current routes).
Merge pull request #142 from sortega/task/155_coinffeine_connection_status

Make MessageGateway to notify coinffeine connection status
Fix a bug in required fiat amount computation in `Order`

We were retrieving zero BTCs instead of zero fiat for ask orders. And the
lack of explicit return type prevented us to detect that.

This fixes the false lack of funds message while submitting an ask order.
Merge pull request #143 from apoloval/fix/OrderSubmissionForm

Fix a bug in required fiat amount computation in `Order`