spacemanager: Allow previously obsoleted values for deprecated srmSpaceManagerEnabled

This patch adds legacy values for srmSpaceManaerEnabled. Thus one can
once again use true, on, yes, enabled, false, off, no, disabled, but
only when using the legacy property.

Also fixed a bug in srm.batch introduced when previously deprecating
srmSpaceManagerEnabled.

Require-book: no
Require-notes: yes
Target: trunk
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/5748/