Pull changes to integrate Natty to Lantern

This uses a flashlight built from the devel branch of [flashlight-build](https://github.com/getlantern/flashlight-build/).  The code in flashlight-build has already been reviewed in the source repos (e.g. flashlight, go-natty, etc.), but no one other than ox has looked at the flashlight-build repo.

It would be good for @myleshorton to rebuild flashlight himself to make sure the build process is good.  Flashlight is still built as before, but you should check out flashlight-build, set it as your GOPATH and then run the builds scripts inside of src/github.com/getlantern/flashlight.

The flashlight-build repo was set up using [gost](https://github.com/getlantern/gost) which could stand to be reviewed too.

Oh, btw, to build flashlight, I recommend using ./buildAndTag so that you can tag it while building.
> Yeah. So we have this dependency on the Java side no matter what, since we're using the exact same mechanism to encrypt the model.

Right -- I'm just saying we want to limit our use of it to make swapping it out easier.



> I'm going to switch it to a hash now. Stay tuned.

Nice!