Make HeaderButton able to have Icon or Image

mobile/package.json

@@ -8,7 +8,7 @@
     "react-test-renderer": "16.2.0"
   },
   "scripts": {
-    "start": "react-native start",
+    "bundler": "react-native start",
     "android": "react-native run-android",
     "ios": "react-native run-ios",
     "test": "node node_modules/jest/bin/jest.js"