Fixes to SaveToGalleryViewController

- discard unused showPlayerNameFields property
- make dialogSize sizing dynamic
Make SaveToGalleryViewController update its layout based on user interface idiom

- compactifies layout to fit iPhone5 screen + keyboard -- appears to work!
- note I wanted to use size classes but phone's vertical size class is Regular just like tablet, which does me no good.
Switch back from Universal app to iPad-only

- the app does work on iPhones, and that's cool. But I did that out of due-diligence, I don't intend to support the iPhone until/unless Apple eliminates non-universal apps from the store.