* Updated ISY component to not overwrite state_attributes.
The ISY component included an ISYDevice base class that is used by all
of the isy994 platforms. This still overwrote the state_attributes
property instead of the more appropriate device_state_attributes
property. This was also repeated in the isy994 light platform. Both of
these were addressed. This also fixes issue #5428.
* Removed custom state attributes from ISY lights.
The brightness attribute need not be manually reported by the isy994
light platform.
* Removed ISY Node cleanup.
The ISY entities don’t really need to unsubscribe themselves while hass
is shutting down. Because these updates are not sent in a thread, there
is no negative impact from shutting down without unsubscribing. This
greatly speeds up hass shutdown.
* Removed unused attribute from isy994 light platform.
* Cleaned up ISY994 light entity class.
1) Removed the state property. This property is set in the Entity base
class and shouldn’t be overridden here.
2) Set the brightness property. This is the proper way of setting the
brightness for the Light base class.
3) Removed properties that are now unused because of these changes.
* Default dimmable brightness to 255 from 100
Full brightness for ISY dimmers is 255. The current 100 value turns dimmer switches on to just under half brightness. Probably just an oversight from the Sept implementation.
* Brightness change for turn_on, ramp for turn_off.
Per discussion with Teagan42 and jbcodemonkey, the brightness should rightfully be None and not an explicit value. There is a continuing issue that the ISY modules don't respect HA's brightness customization values. A new issue will be opened for this.
Additionally, turn_off was using ISY's fastoff() which didn't respect the ramping time. The default behavior should just be off().
1) Modified device tracker entities to allow for attributes to be
overwritten with configuration data.
2) Modified ISY lights to hide brightness when off.
