Unify sorting between all apps and widget tray

- selected locale names are shown before latin
- case independent sorting
- main app > enterprise app

Future possible refactoring:
- Move all the *ItemInfo data structures to model package
- Rename the comparator based on NOT what data structure it supports
but what functionality it supports (locale? case independent?
main app > enterprise app?)

b/21271658
b/20339403

Change-Id: I8a776467392e21d5014e85cd3f51931a3ef89724