recreate the EventBus on restart to avoid classloader leaks

scm-webapp/src/main/java/sonia/scm/event/RecreateEventBusEvent.java

@@ -0,0 +1,7 @@
+package sonia.scm.event;
+
+/**
+ * This event forces the {@link ScmEventBus} to recreate the underlying implementation and to clear all its caches.
+ * Note: After this event is fired, every subscription is removed from the event bus.
+ */
+public final class RecreateEventBusEvent {}