srm: Make login broker of SRM configurable and clean up properties

The patch allows the login brokers used by the SRM to be configurable.
Since the SRM uses two login brokers, one for lookup and one for
registration, I have renamed all related properties such that those
related to door lookup begin with srm.lookup. and those for login
broker registration begin with srm.loginbroker.

When merging into stable branches, the old properties will not be marked
deprecated.

Deprecated by this patch:

srmLoginBrokerUpdatePeriod
srmNumberOfDoorsInRandomSelection

Introduced by this patch:

srm.lookup.loginbroker
srm.lookup.timeout
srm.lookup.population-size
srm.loginbroker
srm.loginbroker.period
srm.loginbroker.threshold
srm.loginbroker.family
srm.loginbroker.version

Target: trunk
Request: 2.6
Request: 2.2
Require-book: yes
Require-notes: yes
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/5604/
pool: Improve logging of common errors

Improve log levels and log messages of common errors found in
production log files.

Target: trunk
Require-book: no
Require-notes: yes
Ticket: http://rt.dcache.org/Ticket/Display.html?id=7685
Acked-by: Paul Millar <paul.millar@desy.de>
Acked-by: Dmitry Litvinsev <litvinse@fnal.gov>
Patch: http://rb.dcache.org/r/5255/
broadcast: Fix expiration of dynamic subscribers

Addresses the issue that HSM cleaner is broken as it newer
receives pool-up notifications.

BroadcastRegistrationTask supplies a relative timeout, but the
broadcast registration cell expects an absolute timeout.

Target: trunk
Request: 2.6
Request: 2.2
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/5601/
(cherry picked from commit 6276fca8040315bcf38e9c77a60e3c87258027e1)
Merge pull request #75 from gbehrmann/fix/2.2/rb5255

pool: Improve logging of common errors
Merge pull request #72 from gbehrmann/fix/2.2/rb5604

srm: Make login broker of SRM configurable and clean up properties
Merge pull request #79 from gbehrmann/fix/2.2/rb5601

broadcast: Fix expiration of dynamic subscribers