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.

I do see one downside to using encryption here - it gives an attacker some potentially useful information for breaking the cipher.  JIDs are fairly short, and if the attacker can discover plain text JIDs to compare with the encrypted versions, that gives them useful information.

I'm going to switch it to a hash now.  Stay tuned.