Bug 26742: Add configuration to koha-conf.xml for message broker

Bug 26742: Add configuration to koha-conf.xml for message broker

The connection details for the message broker should be configurable.
This patch adds configuration options to koha-conf.xml. If they
are not specified, then default connection details will be used.

Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 8663f23a931edea9f8fcd341e67804f613bb1d8d)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>