Include whoisin with other projects

This updates the code base to the one on npm.

It also adds a nice feature, which I'm using in nodebb-plugin-calendar. It allows other plugins to include the whoisin widget in their own projects. 

Usage:

```
var whoisin = require("../nodebb-plugin-whoisin"); 
// the above statement must be executed after NodeBB is done booting up
var html = whoisin.include(unique_id);
// do something with this html: add to webpage, etc.
```