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.
It might make more sense just to use the File class here and to make the directory if necessary, likely in the constructor. Along the lines of:

```java
final File serverConfig = new File(new File(LanternClientConstants.CONFIG_DIR, "pt"), "flashlight-server");
if (!serverConfig.isDirectory() && !serverConfig.mkdirs()) {
    // log an error
}
this.serverConfig = serverConfig.getAbsolutePath();

....

private static String getServerConfigDir() {
    return this.serverConfig;
}
```

Not a big deal, but I'm guessing you must make the directory elsewhere?