if no content-type header for POST request API should return an error message

I have tried to create a priority resource without content-type header but the api created the resource with defaults values and return it with ```status code 200 OK```

example
```json
{
"weight": 0,
"color": "#50A4D8",
"_id": "597cd4aa3118df0004bc3f87",
"createdAt": "2017-07-29T18:32:10.738Z",
"updatedAt": "2017-07-29T18:32:10.738Z",
"uri": "https://dawasco.herokuapp.com/priorities/597cd4aa3118df0004bc3f87"
}
```