Carrot setup

[lbergelson]

PR to test setting up carrot.

@KevinCLydon I took your branch and added some stuff on it

1. A dockerfile that just includes the htsjdk source so we can run tests
2. A super basic test and eval wdl pair that doesn't actually use htsjdk at all
3. I registered them all in carrot.

Now we need to:

1. do the magic binding between carrot/docker/wdl
2. make a real actual test that we can run in carrot