Bug 1201523 - Add grunt-cli to local dependencies list

Normally grunt-cli (a wrapper around grunt to allow it to be easily run
from the command line) would be installed globally, so that it is on the
PATH. However to save having to do this on prod/Heroku/Travis, we
install it locally - and it will then be available via:
`./node_modules/.bin/grunt`
...or else via just `grunt`, if referenced inside a package.json scripts
section.

package.json

@@ -9,6 +9,7 @@
     "grunt": "0.4.5",
     "grunt-angular-templates": "0.5.7",
     "grunt-cache-busting": "0.0.11",
+    "grunt-cli": "0.1.13",
     "grunt-contrib-clean": "0.6.0",
     "grunt-contrib-concat": "0.5.1",
     "grunt-contrib-copy": "0.8.1",