Unset highlight syntax when a folder is selected

When a folder is selected the message
"Please select a file to view its contents" appears with mixed
colors. With this patch this message appears with white color only.

Signed-off-by: Bruno Bottazzini <bruno.bottazzini@intel.com>

client/js/controllers/editor.js

@@ -110,6 +110,7 @@
                         });
                         $scope.root = false;
                     } else {
+                        editor.getSession().setMode();
                         if (data.node.parent === "#") {
                             $scope.root = true;
                             $scope.setEditorContent('Please select a file to view its contents', previousContent, filePath);