code: function getRelationships(payload, resource) {
    var result = {};
    for (var key in resource.relationships) {
      result[key] = getRelationship(payload, resource, key);
    }
    return result;
  }
docs: Fetches specified included data associated to a resource
  
  @param {Object} payload
  The payload encapsulating the included data
  @param {Object} resource
  The resource to find included data for
  
  @return {Object}
  The found included data object(s) keyed by relationships