make sure output buffering is dissabled when using eventsource

lib/eventsource.php

@@ -32,6 +32,7 @@ class OC_EventSource{
 	private $fallBackId=0;
 	
 	public function __construct(){
+		@ob_end_clean();
 		header('Cache-Control: no-cache');
 		$this->fallback=isset($_GET['fallback']) and $_GET['fallback']=='true';
 		if($this->fallback){