Border disappears in pseudobutton's disabled state


![2014-05-28_1332](https://cloud.githubusercontent.com/assets/1333220/3102725/0137f538-e64b-11e3-8f2c-ff91d6cde453.png)
/cc @mishanga 
This is wrong way. You should just remove `important` from here:
https://github.com/bem/bem-components/blob/126deac621f3174566d63530a9d827b97ac21086/design/common.blocks/button/_theme/button_theme_normal.roo#L132