Feature/dump server env

[alainchiasson-guavus]

I found this useful for trouble shooting horizontal scaling issues/load balancing . It prints out the ENVIRONMENT variables that are set on the server.

curl http://127.0.0.1/env

{
  "GUNICORN_CMD_ARGS":"--capture-output --error-logfile - --access-logfile - --access-logformat '%(h)s %(t)s %(r)s %(s)s Host: %({Host}i)s}'",
  "HOME":"/root",
  "HOSTNAME":"27dd06166bc7",
  "PATH":"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
  "SERVER_SOFTWARE":"gunicorn/19.9.0",
  "TAG":"'production'"
}

Not sure if it fits with the goals of httpbin.

[alainchiasson-guavus]

Rebuilding locally and will fix.

[simonkowallik]

I had a similar use-case and previously submitted #543 which prints the hostname and server ip address. I thought about moving to environment variables as well, as defining env variables is straight forward in contrast to container hostname + ip address.