Disqus Support & Updated Favicons

## Disqus

Added support for [Disqus](http://disqus.com/) comments. I didn't include the comment message, as it might be quite long in some cases. Unfortunately, disqus is a bit weird, so we need a user id (which you would normally receive via an oAuth) and an API key.

* to get your user_id (quickly): go to disqus.com, log in, open the
developer console and type: `context.auth.user_id`
* for the api key, create a new [disqus application](http://disqus.com/api/applications/), set the permissions to "read", then copy the *Public Key*

The lifestream config should look like this:
```javascript
{
  service: 'disqus',
  user: '1',
  key: 'someRandomNumb3rsAndLettersInAReallyLongString'
}
```

Christian, if you don' have an account (and don't want to create one either) to get an API key for the example page, I can generate one. The above user id is used in the [api docs](http://disqus.com/api/docs/users/listActivity/).

## Favicons

Updated old icons.