webadmin:  context-sensitive help popups use scrollbars

Changed all context-sensitive help popup windows to force
use of scrollbars. Firefox and Chrome were using scrollbars
automatically, but Internet Explorer was not. Now all three
use scrollbars.

Change-Id: If188b744d3535b0dfc747578d8615e92094891b0
Bug-Url: https://bugzilla.redhat.com/1085943
Signed-off-by: Greg Sheremeta <gshereme@redhat.com>