Made datetime columns bit wider

Author: sreichel

app/code/core/Mage/Adminhtml/Block/Widget/Grid.php

@@ -219,7 +219,7 @@ class Mage_Adminhtml_Block_Widget_Grid extends Mage_Adminhtml_Block_Widget
             'width' => 140
         ],
         'datetime' => [
-            'width' => 140
+            'width' => 160
         ],
     ];