Some final adjustements to configuration properties

Renamed *.enable.spacemanager to *.enable.space-reservation, as
it isn't spacemanager that is enabled by the property, but the
support for space reservations. This also brings the name in line
with a couple of sub-properties in the SRM.

Renamed *.overwrite to *.enable.overwrite and introduced
dcache.enable.overwrite as a common property. This name was already
used in some services.

Renamed srm.service.lookup-loginbroker to srm.protocols.loginbroker.
lookup-loginbroker isn't a service and thus fits badly in the
service.* hierarchy. At the same time, the SRM already got an
srm.protocols.* hierarchy that fits well with the functionality.

Renamed srm.limits.rm.single-remove-batch.size to srm.limits.remove-batch-size.

Added and moved some documentation. Documentation for implicit
space reservation was copied from existing documentation we had
outside the properties files.

Removed properties for implicit and strict space reservations from
transfermanagers service, as they do not appear to make use of these
properties.

Fixed several time unit related bugs (use of milli seconds vs seconds).

Renamed transfermanagers.limits.remote-gsiftp.transfers.max to
transfermanagers.limits.external-transfers and
transfermanagers.limits.copy.remote-copies.max to
transfermanagers.limits.internal-transfers (external transfers are not
limited to gsiftp, and both external and internal transfers are copy
operations).

Renamed transfermanagers.limits.remote-gsiftp.io-queue to
transfermanagers.mover.queue (the queue is not limited to gsiftp
transfers, and this property matches similar properties in other
doors).

Renamed transfermanagers.service.mover.timeout.unit to
transfermanagers.limits.transfer-time (the timeout isn't cell communication
related and there is no service called mover).

Note that old names are not marked deprecated as those names were never
included in an official release.

Target: trunk
Require-notes: yes
Require-book: yes
Acked-by: Dmitry Litvintsev <litvinse@fnal.gov>
Patch: http://rb.dcache.org/r/5848/