Fix missing param for updateCache

Was causing
```no-highlight
TypeError: undefined is not a function
    at /var/www/myproject/node_modules/strider-bower/lib/update-cache.js:13:14
    at /var/www/myproject/node_modules/strider-bower/lib/bower-hash.js:10:14
    at fs.js:207:20
    at Object.oncomplete (fs.js:107:15)
```

Author: Ilya Radchenko

worker.js

@@ -44,7 +44,7 @@ module.exports = {
               return done(err);
             }
 
-            updateCache(context, done);
+            updateCache(context, bowerDirectory, done);
           });
         });
       }