版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/backbone-relational/0.10.0/backbone-relational.js
- https://cdn.bootcdn.net/ajax/libs/backbone-relational/0.10.0/backbone-relational.min.js
Get and set relations (one-to-one, one-to-many, many-to-one) for Backbone models