checkbox + radio: examples with icon (close #351)

Radio:
![2014-04-11_1652](https://cloud.githubusercontent.com/assets/521273/2679756/46385012-c178-11e3-8f5b-c1792f408e60.png)

Checkbox:
![2014-04-11_1653](https://cloud.githubusercontent.com/assets/521273/2679757/47c9cf0a-c178-11e3-896d-cf5640932c74.png)

Normal:
![2014-04-11_1654](https://cloud.githubusercontent.com/assets/521273/2679758/4989b2ce-c178-11e3-91a9-50ce613e39f8.png)