added: Rectangle.aabb

* Calculates the Axis Aligned Bounding Box (or aabb) from an array of points.
*
* @method Phaser.Rectangle#aabb
* @param {Phaser.Point[]} points - The array of one or more points.
* @param {Phaser.Rectangle} [out] - Optional Rectangle to store the value in, if not supplied a new Rectangle object will be created.
* @return {Phaser.Rectangle} The new Rectangle object.
* @static
Merge pull request #1199 from codevinsky/feature/rectangle-aabb

Rectangle.aabb