Decouple networks and datadirs from MainController

[patricklodder]

• Move network/name resolution to it's own class
• Add connectTo() public method to MainController to enable injecting networks (needed if you want to have configurable networks)
• Remove the dependency on CATE inside MainController (was only for datadirs)
• For now, still just use 2 hardcoded networks, but define them in the main class rather than in the controller.