message: [changelog] 0.12.1
diff: ## Changelog
  +### [0.12.1](https://github.com/youzan/vant/tree/v0.12.1)
  +
  +`2018-01-05`
  +
  +**Improvements**
  +
  +* Button: adjust padding of small button [\#511](https://github.com/youzan/vant/pull/511) [@chenjiahan](https://github.com/chenjiahan)
  +
  +**Bug Fixes**
  +
  +* fix Cell icon can't render when no title [\#508](https://github.com/youzan/vant/pull/508) [@chenjiahan](https://github.com/chenjiahan)
  +* fix Cell inner border width [\#506](https://github.com/youzan/vant/pull/506) [@chenjiahan](https://github.com/chenjiahan)
  +* fix CouponList line height [\#507](https://github.com/youzan/vant/pull/507) [@chenjiahan](https://github.com/chenjiahan)
  +* fix CouponList input style [\#502](https://github.com/youzan/vant/pull/502) [@chenjiahan](https://github.com/chenjiahan)
  +* fix Radio icon not clickable [\#505](https://github.com/youzan/vant/pull/505) [@chenjiahan](https://github.com/chenjiahan)
  +
  ### [0.12.0](https://github.com/youzan/vant/tree/v0.12.0)
  `2017-12-29`
  