tools

* add method to set the push token independently from other configuration,
  since the push token can be updated during runtime.
* allow to provide a "clientID" to be sent in push notifications,
  used to demultiplex push notifications to multiple OpenDHT nodes running
  on the same host. For instance Ring uses the accountID as the clientID
  to know which account received the push notification.
* use {"platform":"android"/"ios"} to communicate the platform instead of {"isAndroid":true/false}.