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 instead of unnaturally 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 things within the solid `el` property – excluding the need to use the jQuery's `.find`.