message: Add successful method to Converstaion definition
diff: @@ -154,6 +154,7 @@ declare namespace botkit {
  setVar(field: string, value: any): void;
  silentRepeat(): void;
  stop(status?: ConversationStatusType): void;
  + successful(): boolean;
  transitionTo(thread: string, message: string | M): void;
  }
  interface ConversationCaptureOptions {
  