Automate required attribute spec tests

Database constraints and validation constraints do not always match up. Recently, the `create-policy` command had some discrepancies between what the validation framework considered to be required attributes and what the database required.

It will be helpful to add automated spec testing for required attributes that commands can harness. This should should test, at the least:
- That the command passes with the minimum (required) attributes provided
- That the command fails when any single required attribute is removed