xrootd: Upgrade to xrootd4j 1.3.1

Fixes problems with null-termination of string in xrootd messages.

Target: trunk
Require-notes: yes
Require-book: no
Acked-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Patch: http://rb.dcache.org/r/6669/