Add compatibilty for zepto

Doing few changes is possible to add compatibility for [Zepto](http://zeptojs.com/).

**Observation**: _Zepto's basic implementation of `data()` only stores strings. To store arbitrary objects in the unit tests, it was included the optional ["data" module](https://github.com/madrobby/zepto/blob/master/src/data.js) from custom build of Zepto._

Thanks.