fix(package): update grunt-contrib-coffee to version 2.1.0

Closes #17

Author: greenkeeper[bot]

package.json

@@ -7,7 +7,7 @@
     "ejs": "~2.5.2",
     "grunt": "1.0.1",
     "grunt-contrib-clean": "~1.0.0",
-    "grunt-contrib-coffee": "~1.0.0",
+    "grunt-contrib-coffee": "~2.1.0",
     "grunt-contrib-concat": "~1.0.1",
     "grunt-contrib-copy": "~1.0.0",
     "grunt-contrib-cssmin": "~2.0.0",