Jim Horng

Add callbacks for sent task ack, sent task and reshape API as retrieving result from AsyncResult.get() (fix #38)

1

It's kind of large commit, since the small commits are hard to resolve merge conflicts while creating this PR. ### Give user 3 options to listen for callbacks for async...

針對"公司"為單位的留言

5

目前似乎是以"職缺"為單位的留言，如有"公司"為單位將更有彈性 :)

Support new command:2 message format

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Apple had marked command:1 format(which PyAPNs is currently supported) as [legacy](https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/LegacyFormat.html#//apple_ref/doc/uid/TP40008194-CH105-SW1) and encourage to use command:2 format, see [doc](https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/CommunicatingWIthAPS.html#//apple_ref/doc/uid/TP40008194-CH101-SW4)