Adding scala test integration for servicebox

[cmcmteixeira]

In order to facilitate testing and make service box easier to use in such context, one could provide a set of methods in order to reduce boilerplate.

I propose something like the following methods:

def withServicesUp[F[_]](specs: Spec[F] *)(f: Map[(Service.Ref, Port), Location] => F) : Unit
def withServicesUpUnsafe[F, R](specs: Spec[F] *)(f: Map[(Service.Ref, Port), Location] => R)  : Unit

These methods would essentially

1. start the application
2. wait for all services to be healthy
3. Attempt to run the test defined by f
4. Cleanup the docker state (stopping && removing containers )
5. Propagate the effect final result back to the testing framework

This would potentially allow users to create tests as following

def withApp = ??? //some code that start my application under test
"My app" when "ready" should withServiceBoxUp { config =>
  val dbPort = config(Postgres.ref, Port(5432)).port
  "obey a rule" withApp(config) { app =>
       //testCode goes here
  }

  "obey another rule" withApp(config) { app =>
       //testCode goes here
  }
}

Because we don't want these to clutter the current modules of service box I would also propose adding them in a separate module.

[cmcmteixeira]

Additionally, each of the methods could also register a shutdown hook to cleanup the containers, run the test and, after the cleanup, remove it.