Using Bicubic scaling for upsampling

I got a little too aggressive with FastScale and introduced some visual artifacts at small sizes.

Before:

![dev](https://cloud.githubusercontent.com/assets/226553/3319206/ee2cf9fa-f71d-11e3-8d3c-fad7902b5295.jpeg)

After:

![local](https://cloud.githubusercontent.com/assets/226553/3319207/ef7cb174-f71d-11e3-8ca0-88ae5f3d6fd9.jpeg)