UNOMI-417: fix profile persist when receivint multiple events that modify the profile (#240)

diff --git a/wab/src/main/java/org/apache/unomi/web/ServletCommon.java b/wab/src/main/java/org/apache/unomi/web/ServletCommon.java
index bf700c3..6c48edd 100644
--- a/wab/src/main/java/org/apache/unomi/web/ServletCommon.java
+++ b/wab/src/main/java/org/apache/unomi/web/ServletCommon.java
@@ -96,7 +96,7 @@
                     eventToSend.getAttributes().put(Event.HTTP_RESPONSE_ATTRIBUTE, response);
                     logger.debug("Received event " + event.getEventType() + " for profile=" + profile.getItemId() + " session="
                             + (session != null ? session.getItemId() : null) + " target=" + event.getTarget() + " timestamp=" + timestamp);
-                    changes = eventService.send(eventToSend);
+                    changes |= eventService.send(eventToSend);
                     // If the event execution changes the profile we need to update it so the next event use the right profile
                     if ((changes & EventService.PROFILE_UPDATED) == EventService.PROFILE_UPDATED) {
                         profile = eventToSend.getProfile();