update profile picture update notification

profile picture update notification node now without message node

new node format is like this 

```xml
rx  <notification from="6285643077999@s.whatsapp.net" id="4225590016" type="picture" t="1407113990" notify="Ardian Yuli">
rx    <set jid="6285643077999@s.whatsapp.net" id="1407113990"></set>
rx  </notification>
```