fix(pkg): comma

Make sure the comma is placed correctly when selecting gulp.

Author: stevemao

templates/common/root/_package.json

@@ -56,7 +56,7 @@
     "grunt-usemin": "^3.0.0",
     "grunt-wiredep": "^2.0.0",
     "jit-grunt": "^0.9.1",
-    "time-grunt": "^1.0.0",<% } %>
+    "time-grunt": "^1.0.0"<% } %>,
     "jshint-stylish": "^1.0.0"
   },
   "engines": {