Make it possible to cause node-inspector to listen on HTTPS

Both a key and cert must be specified for the node-inspector. If they are specified, the server will startup listening on https rather than http.
Reduced level of nesting
```js
  checkForFile: function(value) {
    if (!value) return '';

    var realPath = fs.realpathSync(value);
    if (!fs.existsSync(realPath)) throw new Error('The file "' + realPath + '" does not exist');
    
    return realPath;
   }
```