clean up easel.js code

[walterbender]

I learned a lot about JS and Easel.js since writing this test app. Could use a major overhaul.

[sachi-d]

One of the major issues is not using certain features that are in the code
Eg. checking hits on dots - the code is halfway there (hit area) but not competed. How would you want to complete it? We could

1. change the color of the number when hit in the correct order
2. use soundjs to add a sound
3. use a graphical method to indicate it

We could extend the method to indicate when all the dots are completed.

[walterbender]

Would be nice perhaps to add a bit of sound when the dots are hit? Maybe a click sound when the order is correct and a buzz if some sort when out of order.

[sachi-d]

I added sound effects for hitting dots in correct order and finishing the order (Branch addSoundEffects). But soundjs does not work for locally run files (which I found only after working on it since I tested using bracket's live preview).