Add babel plugin to rewrite import paths

Replace 'react-native' imports with direct imports to the relevant
module within 'react-native-web'. Follow up task is to also rewrite
'react-native-web' imports from the entry file to become direct imports
(reduces bundle size).

Close #608

docs/guides/getting-started.md

@@ -34,6 +34,9 @@ const babelLoaderConfiguration = {
     loader: 'babel-loader',
     options: {
       cacheDirectory: true,
+      // This aliases 'react-native' to 'react-native-web' and includes only
+      // the modules needed by the app
+      plugins: ['react-native-web/babel']
       // The 'react-native' preset is recommended (or use your own .babelrc)
       presets: ['react-native']
     }
@@ -71,10 +74,6 @@ module.exports = {
   ],
 
   resolve: {
-    // Maps the 'react-native' import to 'react-native-web'.
-    alias: {
-      'react-native': 'react-native-web'
-    },
     // If you're working on a multi-platform React Native app, web-specific
     // module implementations should be written in files using the extension
     // `.web.js`.