Fixed asset revving issue with css files

tasks/options/clean.js

@@ -1,7 +1,6 @@
 module.exports = function(config) {
   return {
     on_start: ['<%= destDir %>', '<%= tempDir %>'],
-    temp: ['<%= tempDir %>'],
-    docs: ['<%= docsDir %>']
+    temp: ['<%= tempDir %>']
   };
-};
+};