Show file not writable message if editor can't save html because of file permissions

Author: givanz

admin/controller/editor/editor.php

@@ -583,6 +583,10 @@ function save() {
 		if (file_put_contents($fileName, $content)) {
 			$success = true;
 			$text .= __('File saved!');
+		} else {
+			if (!is_writable($fileName)) {
+				$text .= sprintf(__('%s is not writable!'), $fileName);
+			}
 		}
 
 		$cssFile = DS . 'css' . DS . 'custom.css';