spacemanager: Don't rely on AuthorizationRecord

Several spacemanager messages still used AuthorizationRecord rather than the
simpler Subject class. Space manager itself internally also used
AuthorizationRecord.

This patch updates space manager to use Subject directly. All spacemanager
related messages are updated to send Subject rather than AuthorizationRecord.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Dmitry Litvintsev <litvinse@fnal.gov>
Patch: http://rb.dcache.org/r/5684/