Removed public `enqueuePushNotification` methods.
Documented new classes/methods and updated the examples in the README.
Return unsent messages from the retry queue, too.
Separated error handler into two parts so exceptions generated while handling rejected notifications can be handled later in the pipeline. Fixes #37.
Used more direct contact information in an author tag.
Added a note about the lingering GlobalEventExecutor thread (closes #29).
Added a link to the mailing list.
Switched to strong references for registered listeners.
Throw an IllegalStateException when registering a listener for an already-shut-down PushManager.
Merge pull request #40 from relayrides/strong_listener_references

Use strong references instead of weak references for rejected notification listeners
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)
Fixed a minor typo in a comment.
Broaden generic param of rejectedNotificationListener