Support for enhanced notification format about javapns HOT 3 CLOSED

I am also interested in this.  Specifically the expiry information.  We want 
our Notifications to expire at a certain time after they are initially created. 

http://developer.apple.com/library/ios/#documentation/NetworkingInternet/Concept
ual/RemoteNotificationsPG/CommunicatingWIthAPS/CommunicatingWIthAPS.html%23//app
le_ref/doc/uid/TP40008194-CH101-SW4

Note:  current library does use the enhanced notification format, but the 
identifier and expiry values are hardcoded.  Future enhancements could allow 
for those two values to be customized.

Fixed in 2.0 Beta 4.   See new Payload.setExpiry(..) method, and the 
introduction of a new identifier parameter in a few 
PushNotificationManager.sendNotification(..) methods.  Automatic identifier 
generation is also supported in the javapns.notification.transmission classes.

See issue #47 for enhancement request related to error packets.