Add *.cell.export properties

Some services already support the cell.export property for declaring
whether a cell should be exported as well known. This patch adds this
property to all remaining services.

Most users will never touch this property, but it is useful for
non-standard expert deployments.

Target: trunk
Require-notes: yes
Require-book: yes
Acked-by: Karsten Schwank <karsten.schwank@desy.de>
Patch: http://rb.dcache.org/r/5866/