Collision detection

- Added simple collision detection for dom nodes
- Added simple collision detection example

2 events will be triggered when objects collide:
`collisionStart` and `collisionEnd`.

Mini-Example (tbc in planned docs update)
```
$('h1').one('collisionStart', function(evt, collisionData) {
// collisionData
// {
//  collisionType: 'active' or 'passive',
//  collisionWith: <jQueryWrappedDOMnode>
// }
});
```