Minor GUI Improviments

"Standard" name for the frequencies and make it aligned with the control. I think this way is just easier to read and also more "familiar" compared to most of equalizers.
![Captura de tela de 2013-01-04 14:37:12](https://f.cloud.github.com/assets/677051/43573/43c1a04c-568d-11e2-941e-1429b8279ddf.png)