Fix full bleed images on iPad portrait with story list at bottom.

Finally got a bit of time to fix this.  An example of what was broken:

![img_0630](https://cloud.githubusercontent.com/assets/68303/5058838/f208ac94-6cd0-11e4-853e-053eec20e7ba.PNG)

It might make sense to just get rid of the -narrow and -wide stuff for full bleed images and just use numeric widths everywhere; for example I noticed while debugging this that the "500 px" width is actually 499 px.