Unable to specify relationships while creating/updating a resource

[ngseer]

Describe the bug
relationships clause is not allowed in request data model though it's allowed by the spec.

To Reproduce
Steps to reproduce the behavior:

1. Create a new JsonApiRequest model.
2. See there's no ability to add relationships to it.

Expected behavior
Requests like this should be allowed (an example from the spec):

POST /photos HTTP/1.1
Content-Type: application/vnd.api+json
Accept: application/vnd.api+json

{
  "data": {
    "type": "photos",
    "attributes": {
      "title": "Ember Hamster",
      "src": "http://example.com/images/productivity.png"
    },
    "relationships": {
      "photographer": {
        "data": { "type": "people", "id": "9" }
      }
    }
  }
}

[DeanWay]

fixed in 0.10.0, by allowing an optional relationships key on request resource objects, consisting of a mapping of strings to resource linkage data (#15)