Make balls inver direction when colliding
Allow ball to be placed on empty spaces (if a new ball fits)
Use browser's requestAnimationFrame instead of an interval (improves performance)

* More information can be found here http://www.paulirish.com/2011/requestanimationframe-for-smart-animating/
* Define #startAnimateLoop
* Slow balls down 1 pixel (smoothier)
Refactor! Remove Ball.vertical and Ball.horizontal and make the speeds positive or negative - lots of deleted code and less calculations :)
Rename collection to balls
Create Particle for explosions inheriting from Ball
Redefine Particle properties

* Increase generated random numbers to create particles pointing to many different locations
* Remove lifespan - no need
* Fix how gravity works - just need to sum lulz
EXPLOSIONS!

* Explode all Balls that collide creating 25 particles
* Define particles array
* No need to check if ball is collided when creating it anymore - just explode them!
* #tick is kinda big now, maybe a refactoring is a good idea, but I'm sooo tired now :)
* WARNING: Only thing to keep in mind is the call to Object.keys - i think it does not have good support
Merge pull request #1 from brunops/add-collision

Add collision