Restructured configuration system

Configuration logic from node-debug.js moved to config.js
node-debug receive configuration from rc now
config uses yargs argv preprocessor now
Removed conversion part of config.js
Fixed hight priority of node-debug hardcoded defaults
Fixed default web host for node-debug
  (`127.0.0.1` instead of `localhost`)
Fixed null value of web host
  (default web host is empty string now)
Added script option
Added list of avaible options as default help info
The reason is [here](https://github.com/3y3/node-inspector/blob/config/lib/config.js#L6).
I check the parent module of config.js and, if it is ```node-debug.js```, I move to NODE_DEBUG mode. In testing we load config.js with common ```inspector.js``` parent module.