BUG: Events with the same ID will cancel (#13)

With polling, events may not be in chronological order. For each event ID, only one goroutine will be active processing it.

Author: thomasjpfan

service/swarmlistener.go

@@ -204,10 +204,10 @@ func NewSwarmListenerFromEnv(
 		nodeEventChan,
 		nodeNotificationChan,
 		notifyDistributor,
-		NewCancelManager(false),
-		NewCancelManager(false),
-		NewCancelManager(false),
-		NewCancelManager(false),
+		NewCancelManager(true),
+		NewCancelManager(true),
+		NewCancelManager(true),
+		NewCancelManager(true),
 		includeNodeInfo,
 		useDockerServiceEvents,
 		ignoreKey,