Move track handling from Rocketpower to TrackContainer
Rocketpower.java: add constructors and improve Javadocs
Improve Javadocs
Pass TrackContainer to RocketDevices

Also added RocketDevice.debugLog()
Initialize a RocketDevice subclass in RocketPower constructor
Implement GNU Rocket connection setup
Refactor logging to use Java's own logging system (for debugging)

The new system provides much more control on what gets output!