v0.11.0 - Connection pooling, simpler reconnection mechanics

This release represents a significant architectural shift. ApnsClient instances now maintain their own internal connection pools, connect on demand, and will manage all of the reconnection timing on their own. This should make life much simpler for most users, and should open the door to performance gains for industrial-scale users who were previously constrained by running clients on a single thread. This should also fix a host of reported bugs around reconnection and resource usage.

Other changes include:

• Updated to Netty 4.1.14 for the latest bug fixes and performance improvements (#510)
• Restored reference-counted SSL providers, which should resolve issues around direct memory usage and reclamation (#515)
• Added support for building MDM payloads (#516)

For a complete list of changes, please see the v0.11 milestone.