pool: Add missing attributes in replicateOnArrival request

Addresses an issue in the pool's replicateOnArrival feature. If enabled it
failed with an error stating that required attributes where missing.

Target: trunk
Request: 2.6
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/5715/
(cherry picked from commit a4188cfc4e89e2c5310fef52fc16f120d9c915db)
Merge pull request #122 from gbehrmann/fix/2.6/rb5715

pool: Add missing attributes in replicateOnArrival request