support passing a dictionary as the :alert key of a notification
support passing a dictionary as the :alert key of a notification

This doesn't attempt any validation of the dictionary schema as
described here:
http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/ApplePushService/ApplePushService.html

estum/apn_sender,arthurnn/apn_sender,arthurnn/apn_sender,lukeasrodgers/apn_sender