include cross-spawn dep

package.json

@@ -37,6 +37,7 @@
     "babel-preset-es2015-rollup": "^1.1.1",
     "babel-preset-stage-2": "^6.1.18",
     "babel-runtime": "^6.0.0",
+    "cross-spawn": "^4.0.0",
     "css-loader": "^0.23.1",
     "eslint": "^2.2.0",
     "eslint-config-vue": "^1.0.0",