Set target to es5 and module to esnext

Author: Simon Planinschek

tsconfig.json

@@ -1,12 +1,13 @@
 {
   "compilerOptions": {
     "module": "ESNext",
-    "target": "ES6",
+    "target": "ES5",
     "jsx": "react",
     "moduleResolution": "Node",
     "esModuleInterop": true,
     "outDir": "./dist",
     "declaration": true,
+    "strict": true,
     "sourceMap": false
   },
   "include": [