authenticate user via streampusher api

[mcfiredrill]

You'll just need to hit
datafruits.streampusher.com/login.json

with a POST and it will return "success" if the login was successful.

see: https://github.com/datafruits/radio/blob/master/liquidsoap/dj_auth.sh

[mcfiredrill]

https://github.com/dreamsxin/nginx-rtmp-wiki/blob/master/Directives.md#exec_push