Remove global limit on white light temperature (#7206)

* Remove global limit on white light temperature

Here are the supported temperatures of some popular bulbs:

 Philips Hue: 2000K-6500K (the current 500-154 mired range)
 LIFX Color 1000: 2500K-9000K
 IKEA TRÅDFRI: 2200K, 2700K, 4000K

Obviously, Home Assistant cannot enforce a global limit and work properly
with all of these bulbs. So just remove the limit and leave it up to each
platform to work it out.

This commit updates the existing users and adds a clamp to Hue (where the
limit appears to have originated). It does not attempt to update other
platforms that might need extra handling of the larger range that is now
possible.

* Add min_mireds/max_mireds state attributes to lights

* Support min_mireds/max_mireds with LIFX lights

homeassistant/components/switch/flux.py

@@ -17,7 +17,7 @@ from homeassistant.const import CONF_NAME, CONF_PLATFORM
 from homeassistant.helpers.event import track_time_change
 from homeassistant.util.color import (
     color_temperature_to_rgb, color_RGB_to_xy,
-    color_temperature_kelvin_to_mired, HASS_COLOR_MIN, HASS_COLOR_MAX)
+    color_temperature_kelvin_to_mired)
 from homeassistant.util.dt import now as dt_now
 import homeassistant.helpers.config_validation as cv
 
@@ -208,7 +208,6 @@ class FluxSwitch(SwitchDevice):
         else:
             # Convert to mired and clamp to allowed values
             mired = color_temperature_kelvin_to_mired(temp)
-            mired = max(HASS_COLOR_MIN, min(mired, HASS_COLOR_MAX))
             set_lights_temp(self.hass, self._lights, mired, brightness)
             _LOGGER.info("Lights updated to mired:%s brightness:%s, %s%%"
                          " of %s cycle complete at %s", mired, brightness,