* Allow only_cache parameter in zha.safe_read()
* Use cache_only for binary_sensor.zha initial update.
* Use cache_only for fan.zha initial update.
* Use cache_only for sensor.zha initial update.
* Use cache_only for switch.zha initial update.
* Use cache_only for light.zha initial update.
* Refactor cached only read in zha platform.
* Update fan.zha platform.
switch from asyncio to async def()
catch DeliveryError exceptions
keep previous state, if reading 'fan_mode' attribute fails
* fan.zha: Use None for unknown state.
if we fail to read 'fan_mode' attribute, use None for state
