Don't exclude level product attribute (#956)

Author: unicoder88

Helper/Entity/ProductHelper.php

@@ -176,7 +176,7 @@ public function getAllAttributes($addEmptyRow = false)
                 'custom_design', 'custom_design_from', 'custom_design_to', 'custom_layout_update',
                 'custom_use_parent_settings', 'default_sort_by', 'display_mode', 'filter_price_range',
                 'global_position', 'image', 'include_in_menu', 'is_active', 'is_always_include_in_menu', 'is_anchor',
-                'landing_page', 'level', 'lower_cms_block', 'page_layout', 'path_in_store', 'position', 'small_image',
+                'landing_page', 'lower_cms_block', 'page_layout', 'path_in_store', 'position', 'small_image',
                 'thumbnail', 'url_key', 'url_path', 'visible_in_menu', 'quantity_and_stock_status',
             ];