More accurate toolbar button construction

Hi!
I've noted there was some unwanted CSS classes on the _Preview_ button, so I've rewrote toolbar buttons creation routine in a jQuery-way.

_Before:_
![screenshot 2014-09-10 02 53 32](https://cloud.githubusercontent.com/assets/81665/4211209/0619cfb4-3884-11e4-97dc-e9eb5e726820.png)

_After:_
![screenshot 2014-09-10 03 44 24](https://cloud.githubusercontent.com/assets/81665/4211213/0d9c6544-3884-11e4-85e4-8e0470fee2a9.png)

P.S. I use [custom button styles](https://github.com/acelaya/bootstrap2-styled-buttons), that's why my buttons doesn't look like standard BS3 flat buttons.