Add new mixin, and remove duplicate styles

Created by: iamandrewluca

Problem

.main {
  .make-xs-column(12);
  .make-md-column(8);
  .make-lg-column(9);
}
.sidebar {
  .make-xs-column(12);
  .make-md-column(4);
  .make-lg-column(3);
}

Outputs

.main {
    position: relative;
    float: left;
    width: 100%;
    min-height: 1px;
    padding-left: 15px;
    padding-right: 15px;
    position: relative;
    min-height: 1px;
    padding-left: 15px;
    padding-right: 15px;
    position: relative;
    min-height: 1px;
    padding-left: 15px;
    padding-right: 15px;
}

And all media queries with respective width. With new added mixin we use it this way

.main {
  .make-column();
  .make-xs-column(12);
  .make-md-column(8);
  .make-lg-column(9);
}

and we get this CSS

.main {
    position: relative;
    float: left;
    min-height: 1px;
    padding-left: 15px;
    padding-right: 15px;
    width: 100%;
}

I know that this change has a low chance to be merged, but I tried. :)