fix(push plugin): senderId is optional in iosPushOptions
fix(push plugin): senderId is optional in iosPushOptions

closes https://github.com/driftyco/ionic-native/issues/58

klirix/ionic-native,ramonornela/ionic-native,driftyco/ionic-native,xueron/ionic-native,xueron/ionic-native,driftyco/ionic-native,ramonornela/ionic-native,klirix/ionic-native,xueron/ionic-native,klirix/ionic-native,xueron/ionic-native,ramonornela/ionic-native,ramonornela/ionic-native,driftyco/ionic-native