Added `gracefulShutdownTimeout` to `ApnsConnectionConfiguration`.
Added support for shutting down immediately if a graceful shutdown attempt times out. Still need to add tests.
Added a test for graceful shutdown timeouts.
Fixed a copy constructor goof and updated tests accordingly.
Added a clarifying comment.
Merge branch 'close_connections_when_inactive' of github.com:relayrides/pushy into graceful_shutdown_timeout
Fixed more copy constructor mistakes and added some clarifying comments to tests.
Merge branch 'close_connections_when_inactive' of github.com:relayrides/pushy into close_after_send_attempt_limit
Fixed a spelling error.
Added an explicit check for null configurations in the ApnsConnection constructor.
Let us never speak of this again.
Reworded docs for clarity.
Merge branch 'close_connections_when_inactive' of github.com:relayrides/pushy into graceful_shutdown_timeout

Conflicts:
	src/main/java/com/relayrides/pushy/apns/ApnsConnection.java
	src/main/java/com/relayrides/pushy/apns/ApnsConnectionConfiguration.java
Added still more clarifying comments.
Merge pull request #117 from relayrides/graceful_shutdown_timeout

Graceful shutdown timeouts
Merge branch 'close_connections_when_inactive' of github.com:relayrides/pushy into close_after_send_attempt_limit

Conflicts:
	src/main/java/com/relayrides/pushy/apns/ApnsConnectionConfiguration.java
	src/test/java/com/relayrides/pushy/apns/ApnsConnectionTest.java
Updated copy constructor, hashCode, equals, and tests for ApnsConnectionConfiguration.