更新vs-tools到2.0以便支持node12

package.json

@@ -49,7 +49,7 @@
         "jest-serializer-vue": "^2.0.2",
         "np": "^5.1.1",
         "prettier": "^1.18.2",
-        "vc-tools": "^1.0.3",
+        "vc-tools": "^2.0.0",
         "vue": ">=2.5.0",
         "vue-jest": "^2.5.0",
         "vue-template-compiler": ">=2.5.0"