check all assertions

This lets us test endpoints with multiple assertions.  Instead of returning early on a success, this waits for all the assertions to succeed before returning the success.  Here's a sample `:response` object:

```jsos
    "response": {
      "response_code": 422,
      "response_headers": [
        "Content-Type: application/json"
      ],
      "response_body": [
        "\"message\":\"Validation Failed\"",
        "\"field\":\"content_type\""
      ]
    }
```