GOAL: Let the deployment process write one config file, and provide an easy
env path for loading that config in
Add FIRETRACKER_CONFIG_PATH env, which specifies the config file to load
Prefer "production" settings, but add the ability to turn on debug via a
flag in the config (other debug stuff could go in there as well)
Remove the funky interpreter stuff from passenger_wsgi. I believe this was
to support per-virtualenv python versions, which I don't believe we will
be using (and could probably implement a different way)
Config files don't need to support multiple environments, since we write
them out specific to the environment
FIRETRACKER_CONFIG_PATHenv, which specifies the config file to load