Delay opening the main window until after the Destination is loaded.

[macourtney]

At the moment, after you log into Dark Exchange, the main window pops up, but you can't do anything since the destination address has not been loaded yet. It's not obvious this is the problem and it can look like Dark Exchange is not working. It would be nice to delay the main window until the destination address is loaded. However, it would be necessary to give the user feedback on what's going on.