Expose getRGB and getColor somehow?

http://bugs.jqueryui.com/ticket/3806

I would propose that `jQuery.color( '#abcdef' )` return a color object suitable for manipulation/passing to `animate:`

Would allow for something like:

```
var color = jQuery.color( $element.css( 'backgroundColor' ) ).alpha('-=0.5');
$element.animate({ backgroundColor: color });
```
