* Initial proposal for the input_datetime
* Linting
* Further linting, don't define time validation twice
* Make pylint *and* flake8 happy at the same time
* Move todos to the PR to make lint happy
* Actually validate the type of date/time
* First testing
* Linting
* Address code review issues
* Code review: Remove forgotten print()s
* Make set_datetime a coroutine
* Create contains_at_least_one_key_value CV method, use it
* Add timestamp to the attributes
* Test and fix corner case where restore data is bogus
* Add FIXME
* Fix date/time setting
* Fix Validation
* Merge date / time validation, add tests
* Simplify service data validation
* No default for initial state, allow 'unknown' as state
* cleanup
* fix schema
