Wrong labelling of the translation key "errormsg.error.when.unregistering.mbean.0"

The Translation key "errormsg.error.when.unregistering.mbean.0" needs to be changed to "errormsg;error.when.unregistering.mbean.0" (note the change from '.' to ';' after the "errormsg".
This is also how it is spelled in dk.netarkivet.monitor.webinterface.JMXSummaryUtils