spacemanager: Remove obsolete features

Due to the introduction of unique write TURLs, several space manager features
are no longer needed. This patch removes those featurs.

The removed features are all a result of no longer needing the ALLOCATED state
of a file reservation. Thus there is no need to bind file reservations to a
path, no need to track deleted paths, and no need to track lifetime of a file
reservation (the lifetime is now that of the PNFS ID). As a consequence, the
"Already have 1 record(s)" code path no longer exists.

The CLI has been updated to remove the options and output related to the above
features.

The Use and CancelUse messages are no longer supported.

Database schema changes: The path, expiration time, and deleted columns of
srmspacefile have been deleted, together with their indexes. The ALLOCATED
state of srmspacefile records no longer exists.

Target: trunk
Require-notes: yes
Require-book: yes
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6691/