make sure flushing the queue actually flushes it

Author: eplusminus

src/LaunchDarkly/EventProcessor.php

@@ -49,6 +49,8 @@ public function flush() {
 
     $payload = json_encode($this->_queue);
 
+    $this->_queue = array();
+
     return $this->_eventPublisher->publish($payload);
   }