admin: restore current-etc symlink
admin: restore current-etc symlink

It is useful now like it was before, and it is used by the grub
update script.

https://bugzilla.gnome.org/show_bug.cgi?id=690743

gatispaeglis/ostree,sujitfulse/ostree,sujitfulse/ostree,sujitfulse/ostree,resin-io/ostree,resin-io/ostree,GNOME/ostree,leandrosansilva/ostree,gatispaeglis/ostree,gatispaeglis/ostree,leandrosansilva/ostree,GNOME/ostree,gatispaeglis/ostree,resin-io/ostree,resin-io/ostree,resin-io/ostree,GNOME/ostree,leandrosansilva/ostree,leandrosansilva/ostree,sujitfulse/ostree,gatispaeglis/ostree,GNOME/ostree,GNOME/ostree,gatispaeglis/ostree,leandrosansilva/ostree,sujitfulse/ostree