allow model.defineProperties to be called with an object and allow the p...

allow model.defineProperties to be called with an object and allow the property to have a string for the type instead of an object.

Example:
this.defineProperties({
    dashboard_id: 'string',
    user_id: 'int',
    title: 'string',
    columns: 'int',
    created_time: 'int'
  });