Add extra values to passport record

Hello, 

The generator is limited to the strict minimum. I wanted a flexible way to define what passport must saved. I  inspired by HWI/OAuthBundle for Symfony. 

This is not necessarily the best method to implement this feature but I try to do something.
I am a newbie on NodeJS, Sails.

The principle is to define the mapping informations in a section `paths`: 
* `jsonname` is the key in `profile._json` 
* `localname` is the name of the value in the model/record


For exemple :
```js 
github: {
     name: 'GitHub',
     protocol: 'oauth2',
     strategy: require('passport-github').Strategy,
     options: {
       clientID: 'your-client-id',
       clientSecret: 'your-client-secret'
     },
     paths: {
       jsonname: 'localname'
     }
   }
```