* Add mysensors notify platform
* Make add_devices optional in platform callback function.
* Use new argument structure for all existing mysensors platforms.
* Add notify platform.
* Update mysensors gateway.
* Refactor notify setup
* Enable discovery of notify platforms.
* Update and add tests for notify component and some platforms.
* Continue setup of notify platforms if a platform fails setup.
* Remove notify tests that check platform config. These tests are not
needed when config validation is used.
* Add config validation to APNS notify platform.
* Use discovery to set up mysensors notify platform.
* Add discovery_info to get_service and update tests
* Add discovery_info as keyword argument to the get_service function
signature and update all notify platforms.
* Update existing notify tests to check config validation using test
helper.
* Add removed tests back in that checked config in apns, command_line
and file platforms, but use config validation test helper to verify
config.
* Add a test for notify file to increase coverage.
* Fix some PEP issues.
* Fix comments and use more constants
* Move apns notify service under notify domain
