Add missing i18n EN

duniter4j-es-user/src/main/resources/i18n/duniter4j-es-user_en_GB.properties

-duniter.event.NODE_BMA_DOWN=
-duniter.event.NODE_BMA_UP=
+duniter.event.NODE_BMA_DOWN=Duniter node [%1$s\:%2$s] is DOWN: no access from ES node [%3$s]. Last connexion at %4$d. Blockchain indexation waiting.
+duniter.event.NODE_BMA_UP=Duniter node [%1$s\:%2$s] is UP again.
 duniter.event.NODE_STARTED=Node started on cluster Duniter4j ES [%s]
 duniter.user.event.active=
 duniter.user.event.cert.received=