update handlebars to avoid security issue (#1521)

package.json

@@ -61,7 +61,7 @@
     "bootstrap": "^3.3.7",
     "d3": "^3.5.17",
     "font-awesome": "^4.7.0",
-    "handlebars": "^1.3.0",
+    "handlebars": "^4.0.11",
     "i18next": "^4.2.0",
     "i18next-browser-languagedetector": "^1.0.1",
     "i18next-xhr-backend": "^1.3.0",