Update Tictactoe.js

I created a method called `play` for semantics purposes – when you click on play, you should do some process which starts the game, you shouldn't hide the modal nor restart the game within the modal hiding's method.

After all, I excluded `.find()` method to DRY. When you have `$.el` correctly up and running, you can use `this.$` to find within the `el` property – excluding the need to use the jQuery's `.find`.
Merge pull request #2 from chiefGui/patch-1

Update Tictactoe.js
Created first A.I. method -> setCpuPlayer
Added sounds and created option to play multi or against the cpu