v0.6.0: Handle connection drops gracefully

What's Changed

• Implement async_unload_entry to allow clean unload/reload by @malakudi in #54
• On connection troubles, disable entities instead of completely locking up HomeAssistant. They'll be re-enabled later. This change made our entire code asynchronous, which will cause things to run much smoother as well.

New Contributors

• @malakudi made their first contribution in #54

Full Changelog: v0.5.16...v0.6.0