dcache: alarms: Extend log level capture to all levels; fix server-side logging

module: dcache, package alarms

Because of issues that were not working with the Turbo Filter, the Alarm definition was implemented to accept only messages at WARN or ERROR levels.  It is preferable to allow an ALARM to be defined against any logging level.

I have retested the Turbo Filter and it is now working as advertised.  This patch

- moves the alarms.remote-logging.level property to the level element of the remote appender in the TurboFilter, where it belongs, and eliminates the extra filter on the appender itself;
- makes the necessary modifications to allow ALARMS to be captured at any level, even though ERROR and WARN will undoubtedly be the most common (and even though to capture those below the WARN level one risks a considerable amount of congestion on the alarm server; in such a case it is advisable not to use the XML store).

The logback-server.xml has also been adjusted so that:

- the log file messages are fuller and resemble the optional MAIL message;
- events from the server's own domain are excluded from the store and the history and are placed in the server.log

Testing:

On testbed.  Tested by varying the levels of alarms.remote-logging.level (set globally in the dcache.conf file) and observing the results in the history.log, server.log and on the webadmin page.  Also added an arbitrary ALARM defined at INFO level and observed it appear on the page when the remote logging level was low enough.

Target: master
Patch: http://rb.dcache.org/r/5522
Require-book: yes
Require-notes: yes
Acked-by: Gerd
Request: 2.6

RELEASE NOTES:
BOOK:

Alarms can now be defined at all logging levels.  However, the volume of traffic sent to the server (where the logging message is captured and converted into a potential alarm) increases dramatically below the WARN level.  If this kind of alarm is desired, it is advisable to run the RDBMS version of the store, as the XML store fills up to scores of pages very quickly and searching becomes slow.  Logging messages from the logging server and the domain in which it runs are not sent to the store, but are written to the server.log.