Sort by most used. Alphabetical sort is case-insensitive (Rebased and Updated)

(This is an updated version of PR #23 - I put it in a different request because I rebased it on top of many months of commits in master, and so stuffed the history of the previous branch. I'm not enough of a github user to figure out how best to deal with that :) I think I've addressed the issue I was having when we left off before.)

The most used apps are calculated by incrementing a counter (in a shared
preferences file called launch_history.xml) each time an app is launched
via FAST. Also changed the alphabetical search to be case-insensitive.

Changed 'most popular' to 'by usage'