loginbroker: Register root path of doors

The patch adds the root path of each door to the information registered in
loginbroker.

The following properties are obsolete:

srm.service.webdav.root
srm.service.xrootd.root

Target: trunk
Require-notes: yes
Require-book: yes
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6641/