Use nconf for configuration management

[Marak]

We should replace the current argument parsing with optimist and replace it with nconf.

This will allow http-server to be configured via the command line, or a config.json file, or any other transport nconf supports.

[BigBlueHat]

We'll need to re-do the work in #131, but getting onto something more current/used would help us avoid likely security issues in the future.

[thornjad]

I still support moving to nconf, though there have been significant changes since #131 which probably require a complete restart of that work.