Update all dependencies to latest + Fix tar vulnerability

Manually tweaked the `node-sass > node-gyp > tar` dev vulnerabillity in `package-lock.json`, as latest `node-sass` hasn't addressed it yet.

Author: Oblosys

examples/parent-child-demo/package.json

@@ -12,9 +12,9 @@
   },
   "dependencies": {
     "prop-types": "^15.7.2",
-    "react": "16.8.5",
-    "react-dom": "16.8.5",
-    "react-hot-loader": "4.8.0",
+    "react": "16.8.6",
+    "react-dom": "16.8.6",
+    "react-hot-loader": "4.8.4",
     "react-lifecycle-visualizer": "^2.2.1"
   }
 }