Apply CSS enhancements in build time

[gustavohenke]

CSS enhancements should be done when building bselect.
The goal is to eliminate cases where a selector has 2 properties of the same type, for example:

.bselect {
   padding: 4px 10px;
   padding-left: 15px;
}

Will try to find out how to do that with Grunt.

[gustavohenke]

https://github.com/operasoftware/ucss is able to find out unused rules... who knows