archive: Fix display_name of root entry
archive: Fix display_name of root entry

Change display-name file info property from "/ on XYZ" to
"/ in XYZ", as indicated by the FIXME in the code.

https://bugzilla.gnome.org/show_bug.cgi?id=770238

gicmo/gvfs,gicmo/gvfs,gicmo/gvfs,gicmo/gvfs