'Lock down' api with additionalProperties and required

Go through microsetta_private_api.yaml and add `additionalProperties: false` to all schemas (including inputs and responses) that will NOT accept any properties not laid out in the api (which I think is all of them). Also add `required` sections to each schema (as was done with `address`) to indicate which fields MUST be present (see https://stackoverflow.com/a/45577763 for details on what `required` actually validates).

Test these additions by sending input json with too many or too few fields (NOT the examples in the yaml, which should all be valid) and see whether connexion correctly screams.