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 `--script` option is a way to manage enviroment (not `process.ENV`) of script from rc. For example:

```js
//$ node-debug app
/* local or global rc configuration
{
  script: ['debug-mode']
}
*/
...
if (argv.debugMode) {
  someResponse.bigArray = smallFakeArray;
}
...
```

The second reason to add this option - avoid argv parsing outside of `config.js`
It's not an important feature, I can exclude it, if you want.