OOIION-1694: Handle [None] being returned from read_states()

@edwardhunter

The `strict=False` parameter is being is passed to `read_doc_mult` in this execution chain. This can potentially result in a list being returned that contains `None` values (ie. `[None]`). `get_operational_state` is not taking this into account. It is only catching the case when `[]` (False) is returned, not when `[None]` (not False) is returned. 

https://jira.oceanobservatories.org/tasks/browse/OOIION-1694