Chaostoolkit-lib

Changed

- Allow for missing environment variable when `default` property is set, even
to a `None` value

Fixed

- Converting using JSON is a bypass when value is an empty string or `None`

Added

- When declaring an environment variable in a configuration block, you can
ask Chaos Toolkit to convert the value read (which is always a string) into
an appropriate type: int, float, str, bytes, bool and json

json
{
"my_var": {
"type": "env",
"key": "SOME_VAR",
"env_var_type": "int"
}
}

Fixed

- When a var file has no extension, it couldn't be properly parsed because
we searched for an empty string into a string sequence, and that was
truthey [263][263]

[263]: https://github.com/chaostoolkit/chaostoolkit-lib/issues/263

Changed

- Set the status of the experiment to `completed` when we deviated but tolerances
did not fail. Only set the status to `failed` if one of the tolerance
actually failed to execute. [258][258]
- The order of applying controls. Before, global controls were applied after
experiment controls. This has been changed so global controls get applied
first. This was never specified so let me know if you get errors.

[258]: https://github.com/chaostoolkit/chaostoolkit-lib/issues/258

Changed

- Removed restriction on the `importlib-metadata` package