GATEWAYS was a dict, so would overwrite item if key was the same. This
would happen when using multiple MQTT gateways, since the device id is
the same (`mqtt`).
* Fix by changing GATEWAYS from dict into list.
* Use hass data to store mysensors gateways instead of having GATEWAYS
be a global.
* Separate platform and presentation units in climate
* Fix unit tests
Maybe
* Fix unit tests some more
Maybe
* Rename _platform_unit_of_measurement to temperature_unit
* Fix tests for renamed attribute
* Added Support for mysensnors Climate/HVAC device
* Added Support for mysensnors-hvac device:fix pylint error
* Added Support for mysensnors-hvac device:fix pylint error2
* Fixed Issues in code as per review comments
* Fixed Linter Errors
* Fixed Linter Errors:2
* Fixed Linter Errors:2
* Fixed Linter Errors
* Fixed Linter Errors
* Fixed Linter Errors
* Added Support for MySensors HVAC| Fixed Review Comments| Removed Additional Comments
* Added Support for MySensors HVAC| Fixed Review Comments Itr2
* Changes to correctly support devices with both high and low bound temperatures
* Changed to optimize the code
