webadmin: fix path comment style in domain dialog

Fixed alignment issues of path comment label in
domain dialog (affects posix/nfs/gluster storage types).

Before-Screenshot: http://i.imgur.com/jdNIuIq.png
After-Screenshot: http://i.imgur.com/dTPf0Bk.png

Change-Id: Ie200eaef877260967faba45131261097912bbe1d
Signed-off-by: Daniel Erez <derez@redhat.com>