Build: Remove redundant grunt-cli dependency

This is already providewd by grunt, which actually installs one
patch version newer, and so was even installed twice.

Author: Krinkle

package-lock.json

@@ -25,7 +25,6 @@
   },
   "dependencies": {
     "grunt": "1.5.3",
-    "grunt-cli": "1.4.2",
     "grunt-jquery-content": "3.1.0"
   }
 }