Added a separate queue for notifications that need to be re-sent.
Swapped the order of queue reads so we drain the retry queue before trying to send new notifications.
Merge branch 'master' into separate_retry_queue

Conflicts:
	src/main/java/com/relayrides/pushy/apns/ApnsClientThread.java
	src/main/java/com/relayrides/pushy/apns/PushManager.java
Added the beginnings of a PushManagerFactory.
Removed public `enqueuePushNotification` methods.
Documented new classes/methods and updated the examples in the README.
Return unsent messages from the retry queue, too.
Used more direct contact information in an author tag.
Merge branch 'master' of github.com:relayrides/pushy into separate_retry_queue

Conflicts:
	src/main/java/com/relayrides/pushy/apns/PushManager.java
Merge pull request #38 from relayrides/separate_retry_queue

Separate retry queue (fixes #20)