Add health check API

[Relrin]

In actual moment of time microservice-strategist doesn't have any public API for external resources which is doing health checks to each existing node in the cluster. So, it will be great to implement this extra functionality.

So, I'm proposing two possible ways to do that:

• Replace the existing custom Application onto full-featured Sanic application, so that the server will work on default HTTP/HTTPS ports with health check API and background tasks for AMQP workers. This way is the most preferrable, however you will need to port some tests as well (so that they will user Sanic server during tests execution)
• Add Sanic server with APIs as the background task to event-loop