title: How do I update a list data_relation in Python Eve
body: <p>I have a model 'users' and a schema for it, which includes a one-to-many relation back to users:</p>
  
  <pre><code>'followers': {
      'type': 'list',
      'schema': {
              'type': 'objectid',
              'data_relation': {
                      'resource': 'users'
              }
      }
  },
  </code></pre>
  
  <p>I am trying to update the list of followers. I tried sending PATCH request to the <strong>/users/545c7dccb505970bbf0e5ad1</strong> endpoint with a 'followers' key and a list of objectids but it doesn't work. Also tried sending a PUT request to <strong>/users/545c7dccb505970bbf0e5ad1/followers/</strong> but no luck. </p>
  
  <p>So how do I add an object to this list with Python Eve REST API?</p>
  
  <pre><code>GET /users/545c7dccb505970bbf0e5ad1/
  {
      "_updated": "Fri, 07 Nov 2014 08:07:40 GMT",
      "public_key": "test",
      "_etag": "256d6da738a0f39929d40d1c868e1f67661460be",
      "_links": {
          "self": {
              "href": "/users/545c7dccb505970bbf0e5ad1",
              "title": "User"
          },
          "parent": {
              "href": "",
              "title": "home"
          },
          "collection": {
              "href": "/users",
              "title": "users"
          }
      },
      "active": false,
      "_created": "Fri, 07 Nov 2014 08:07:40 GMT",
      "_id": "545c7dccb505970bbf0e5ad1"
  }
  
  PATCH /users/545c7dccb505970bbf0e5ad1
  {
      "_status": "ERR",
      "_error": {
          "message": "You don't have the permission to access the requested resource. It is either read-protected or not readable by the server.",
          "code": 403
      }
  }
  
  PUT /users/545c7dccb505970bbf0e5ad1/followers
  {
      "_status": "ERR",
      "_error": {
          "message": "The requested URL was not found on the server.  If you entered the URL manually please check your spelling and try again.",
          "code": 404
      }
  }
  </code></pre>