GPII-716: PCP's method for interaction with FM via WebSockets should be more declarative

Link to JIRA: http://issues.gpii.net/browse/GPII-716

This pull request is strictly connected with Websockets communication from PCP to FM (http://issues.gpii.net/browse/GPII-539) and is not related to the pilots.
I don't think this component will be used by PMT, thanks for the point though.