Trebuchet : Show notification for new icon packs

Notify user of compatible icon packs and allow
them to apply upon install.

Change-Id: If8ac1f9b9be7ce9f215fb2ccc63e7fe88a185eba
Trebuchet : Allow user to reset custom icons

When a icon theme is applied, allow user to reset any custom icons
so that the theme's icon can show instead.

Change-Id: Ic1660fafe41aa3447fb755cd36a352f5af295931
Trebuchet : Icon edit dialog fixes

Append text rather than setText for the edit dialog title, so that the
cursor moves to the end.

Keep track of customIconResource state to ensure its not reset.

Preserve custom icons when the linking application is updated

Change-Id: Icab0f0ce45f1dbb79ce895228303aa2c944f1213