Miflora (#3053)

* First version of the MiFlora sensor (not yet finished)

* First workign version

* Added some documentation
Get name from sensor, if not defined

* Ignore IOError

* Added force_update option

* Updated comments

* Renamed fertility to conductivity (what it really is)

* MiFlora library update

* Updated helper files

* Formatting

* Fixed pylint errors

* Removed default from monitored conditions

* Removed KeyError handling as a KeyError should never be raised

* Added a return when no data is received

* emoved unnecessary return statement

* Changed default name

* Changes quotes and string operation ( @Teagan42 )

* - number of samples for median calculation is now configurable
- set state to None if no data could be polled from sensor

* Bugfix in library
more logging

* Fixed miflora version number