TestFlight script

Here's my updated version of a TestFlight upload script. It's based on your hockey script, but informed from our existing bash TestFlight script. I've tested a few times using the same after-build trigger script that you described and it works great! There's enough in common with these scripts that a common set of base functionality could be extracted, but that might be overkill.

Thanks for starting this repo, it's really helpful!

The environment variables are:

* CMD_API_TOKEN
* CMD_TEAM_TOKEN
* CMD_DISTRIBUTION_LISTS