Add recursive

Author: vladikoff

lib/grunt/file.js

@@ -371,7 +371,7 @@ file.delete = function(filepath, options) {
   try {
     // Actually delete. Or not.
     if (!nowrite) {
-      fs.rmSync(filepath);
+      fs.rmSync(filepath, { recursive: true, force: true });
     }
     grunt.verbose.ok();
     return true;