The -1 default was getting stored to the database.
Also removes the other rulesets' HitObjectComposers for now.
Fixes https://github.com/ppy/osu/issues/476.
Used to get correct bindings for a mode (ActionMappingInputManager).
This also - Renames TextAwesome to SpriteIcon. - Removes the default size of "20" from SpriteIcon (now defaults to the underlying texture size).