set graphite back to default backend

exampleConfig.js

@@ -54,6 +54,6 @@ Optional Variables:
   graphitePort: 2003
 , graphiteHost: "graphite.host.com"
 , port: 8125
-, backends: [ "./backends/repeater" ]
+, backends: [ "./backends/graphite" ]
 , repeater: [ { host: "10.8.3.214", port: 8125 } ]
 }