target_temp_step seems to break Awesome Thermostat

[JerseyJames]

The notes for configuration suggest that any variable permitted by 'Generic Thermostat' is accepted by 'Awesome Thermostat' but when I add the 'target_temp_step' variable in to my config the thermostat breaks.

It would be useful to have this supported as I'd like the 'Precision' (which works) set to 0.1 (so I can see the exact temperature) but have the configurable temperature a bit less accurate (eg. 0.5). This is mainly to improve the usability on a touch interface where you don't have the accuracy of a mouse.

Hopefully my testing has been accurate here and I'm not wasting anyones time by missing something. 'Awesome' component generally though. :-)