* First pass on providing individual services for all possible targets that a notification platform supports.
* Add a quite hacky first version of notification groups
* Add a docstring for get_targets
* Register group service under notifygroup/ and safely check for notifygroups in config
* Remove notifygroups, because it belongs in its own PR
* Make @balloob requested changes
* get_targets()->targets
* Add tests for notify targets exposed as individual services
* If we dont have a platform name set in configuration, lets use the name of the platform instead of notify
* Fix test docstring.
* Dont use a dictionary for just one value
* No need to double slugify
* targets is now just a list of strings instead of a dict
* Log error for services called without required attributes, in
media_player, notify and thermostat platforms.
* Add fan property and methods in thermostat demo component.
* Add tests for notify file and thermostat demo component.
* Increase coverage of tests for media_player, notify and thermostat
platforms.
* Fix some PEP issues, but not all. Tests still have old linting
errors.
