Bug fix for grid scaffolding if you want to redefine the sizing in media queries

Needs new width and gutter passed back into mixin to work properly.

Example:
// iPad (Landscape)
@media only screen 
	and (min-device-width : 768px) 
	and (max-device-width : 1024px) 
	and (orientation : landscape) {
	
	// GRID SETUP
	@grid_columns: 12;
	@column_width: 60px;
	@gutter_width: 8px;
	
	.one_full { .grid_columns(12, @column_width, @gutter_width); }
	.one_half { .grid_columns(6, @column_width, @gutter_width); }
	.one_third { .grid_columns(4, @column_width, @gutter_width); }
	.one_quarter { .grid_columns(3, @column_width, @gutter_width); }
	
	.two_thirds { .grid_columns(8, @column_width, @gutter_width); }
	.three_quarters { .grid_columns(9, @column_width, @gutter_width); }
}