Add text shadow to message dialog that match real PSP

![screen00007](https://f.cloud.github.com/assets/3000282/692365/46d50a14-dc1e-11e2-8af5-3f3114b157d1.jpg)

![screen00008](https://f.cloud.github.com/assets/3000282/692366/5549af64-dc1e-11e2-9e8c-e768e6ff5ac0.jpg)