Fix dependencies

Author: cmgustavo

package.json

@@ -8,6 +8,11 @@
   "devDependencies": {
     "bitcore-wallet-client": "5.1.2",
     "browserify": "^9.0.8",
+    "grunt": "^1.0.1",
+    "grunt-contrib-clean": "^1.1.0",
+    "grunt-contrib-concat": "^1.0.1",
+    "grunt-contrib-copy": "^1.0.0",
+    "grunt-contrib-uglify": "^2.3.0",
     "uglify": "^0.1.1"
   },
   "repository": {