Fixed error handling in geo ip lookup closes #2011

Mind taking a look at this @aranhoide?
So the reason for this is twofold:

1. A legacy from when Flashlight didn't know anything about masquerades and when Lantern would pass it the masquerade to use
1. The java side still handles the geo IP lookup because it has to decide what mode to run in and to start flashlight accordingly. To do that in a blocking-resistant way it need to use domain fronting.

This will all happen at the Go layer eventually of course, but for now it's one of the first things that gets called, and the Go code hasn't even started yet.