* Fix plant MIN_TEMPERATURE, MAX_TEMPERATURE validation
small_float only allows values from 0 to 1 so we should use float instead
* Do not use vol.All for a single validation
* new implementation without mqtt
* fixed lint findings
* fixed more lint findings
* fixed final flak8 error
* added unit tests for platform "plant"
* - changed status to "OK" / "problem"
- added attribute "problem" with details on the problems
- removed unused constant
- setting icon to "?" until we have meaningful data
* reformatted code to meet line length requirements
Marc Egli
Fabian Affolter
ChristianKuehnel