Phaser.Tween.from

Added a reverse tweening function that will accept properties of where you want to start the tween from and will end the tween at the current property or properties of the object that the tween is operating on.

Usage:

```javascript
var sprite = game.add.sprite(game.world.centerX, game.world.centerY, 'yeoman');
game.add.tween(sprite).from({x: 0 - sprite.width}, 1000, Phaser.Easing.Bounce.Out, true);
```