Fixed a bug where the mock feedback server wouldn't close the connection if no expired tokens were written.
Removed redundant received notification count checks (the latch accomplishes the same thing).
Cleared up separation of responsibilities for error handling in the mock server.
Got rid of the hacky failWithErrorAfterNotifications method.
Clarified that the countdown latches from the mock server are for ACCEPTED notifications.
Made an explicit event loop group a requirement for mock servers.
Don't shut down worker groups unless we really have to. This speeds up tests dramatically.
Made some cleanup steps more explicit.
Fixed a potential race condition where the close listener could be attached after the write had already completed.
Merge branch 'threadless_connections' into mock_server_robustification
Merge branch 'threadless_connections' of github.com:relayrides/pushy into mock_server_robustification

Conflicts:
	src/test/java/com/relayrides/pushy/apns/BasePushyTest.java
	src/test/java/com/relayrides/pushy/apns/FeedbackServiceClientTest.java
Merge branch 'threadless_connections' into mock_server_robustification
Merge pull request #54 from relayrides/mock_server_robustification

Mock server robustification (closes #49)