Revert "Revert "3.14: Move gnome-icon-theme to -world, no module depends on it""

This reverts commit 1d194404eaece533a6dffe5266d7e4d9bf7b460b; the 3.12 branch
now supports adwaita-icon-theme.
Revert "Revert "apps-3.14: evolution doesnt depend on gnome-icon-theme anymore""

This reverts commit d0c26b74ce759e214681fcd15be74fa7500bc49f; the 3.12 branch
now supports adwaita-icon-theme.