We were using the Draft4Validator in one place, so this updates it to
the Draft7Validator instead.
The schemas were mostly using draft 4 of the JSON schema, though there
were a couple of schemas that were already of version 7. This updates
them all to version 7, which is the latest version fully supported by
the jsonschema Python package. There are some breaking changes in the
newer version of the schema, but I could not see anywhere would these
affect us. Some of these schemas were not valid in version 4, but are
now valid in version 7 because `"required": []` was not valid in earlier
versions.
Emualated the validation methods that exist [in the python-client](620e5f7014/integration_test/__init__.py).
The `validate_v0` function loads json schemas from a local
`/schemas` directory, whereas the new `validate` function (which
we're going to use for our v2 API calls) uses the common
`get_notification_response` python schema defined in
"app/v2/notifications/notification_schemas.py".
Removed the new `v2` schema from the last commit as it's no longer
being used.
Also, refactored common code in the GET and POST contract files
so that making requests and converting responses to JSON are
pulled out into common functions.