This lets components declare their precision for temperatures. If
nothing is declared, we assume 0.1 C and whole integer precision in
F. Currently this supports only WHOLE, HALVES, and TENTHS for
precision, but adding other precision levels is pretty straight
forward.
This also uses proliphix as an example of changing the precision for a
platform.
Closes bug #4350
* 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