Add the ability to trigger a requisition import via the Karaf shell

In the Karaf shell, we can current show requisitions using the provision:show-import command, but there's no way to actually trigger an import for these.

To manually trigger the requisition, we currently resort to using send-event.pl with something like: ./bin/send-event.pl uei.opennms.org/internal/importer/reloadImport --parm 'url requisition://opendaylight'

We should be able to do this easily directly in the Karaf shell.