Add subtle background pattern

Snazzy!
Reposition elements to make room for more dice

I didn't like that there was only room for ~10 single results so I made it
possible for the element to grow, making room for 24 dice results.
Add showing of random rolls

A common complaint about the app was that you weren't always aware of whether
the app had rolled, especially when the result would be the same. This
"animation" ensures that you're aware that the app has rolled.
Sort the dice results array

This makes it easier to pull out single results from the results list.

Fixes #10
Add manifest file for Firefox OS

Fixes #3