added exceptions to dba class

added exception handling to index.php, please mind that there is no
recovery at the moment
added transactions to db update. Please mind that they might not be
supported by db table engines. 
added admin email on failed updates

added german translation for admin email

index.php

@@ -11,6 +11,7 @@
  * bootstrap the application
  *
  */
+try {
 
 require_once('boot.php');
 
@@ -370,3 +371,9 @@ else
 
 session_write_close();
 exit;
+} catch(Exception $ex) {
+// it may fail because logger uses the db, 
+// but give it a try: 
+logger('exception caught at index.php: '.$ex->getMessage()); 
+system_unavailable(); 
+}