Add support for testing lantern to ooniprobe

We should test to see if lantern is working properly.

It requires java so we should see if raspberry pi will work properly with it.

Ox Cart says:

It's just an HTTP proxy and you can run it on whatever port you like - just set the -addr to whatever you like (default localhost:8787).

The most recent version that we're distributing to Iran is here - https://github.com/getlantern/flashlight-build/tree/valencia

Open questions are:

How can we learn if lantern has successfully bootstrapped
What debug information can we get from the software that would allow us to understand why and how it is being blocked