bugfix: Handle NonNull/List Types Properly

[bradschwartz]

Fixes where NonNull and ListTypes were defaulting to scalar types, because we were returning field_type for their kind, which is just that objects name.

Looking at the schema.json fixture for Droid (updated test):

{
  "args": [
    {
      "defaultValue": null,
      "description": null,
      "name": "episode",
      "type": {
        "kind": "NON_NULL",
        "name": null,
        "ofType": {
          "kind": "SCALAR",
          "name": "String",
          "ofType": null
        }
      }
    }
  ],
  "deprecationReason": null,
  "description": "Get droids for episode",
  "isDeprecated": false,
  "name": "droidsInEpisode",
  "type": {
    "kind": "LIST",
    "name": null,
    "ofType": {
      "kind": "OBJECT",
      "name": "Droid",
      "ofType": null
    }
  }
}

Previously, the field_kind function would return Droid. Now, it will properly return OBJECT and links will render properly.