Merge pull request #1018 from nivin-studio/2.0

修复：设置Column width为0时显示错误

src/Layout/Column.php

@@ -112,7 +112,7 @@ class Column implements Renderable
     {
         // get class name using width array
         $classnName = collect($this->width)->map(function ($value, $key) {
-            return "col-$key-$value";
+            return $value == 0 ? "col-$key" : "col-$key-$value";
         })->implode(' ');
 
         return "<div class=\"{$classnName}\">";