Fix jquery attribute equals selector.

@maethu 

![bildschirmfoto 2014-02-10 um 14 27 08](https://f.cloud.github.com/assets/557005/2125749/117e9494-9257-11e3-9d6e-d7aed546eb54.png)

JQuery API implementation: http://api.jquery.com/attribute-equals-selector/

closes #13