SimplePush Notifier, subscribe does nothing with "callback"

In the aerogear.simplepush.js, where the notifier subscribe method happens,
https://github.com/aerogear/aerogear-js/blob/master/src/simplepush/aerogear.simplepush.js#L94

the "callback" parameter, doesn't seem to be used at all.
https://github.com/aerogear/aerogear-js/blob/master/src/notifier/adapters/simplePush.js#L372

probably can be removed