Add build script

tools/build.js

@@ -0,0 +1,16 @@
+const { execSync } = require('child_process')
+
+console.log('Building CommonJS modules ...')
+
+execSync('rimraf lib && babel ./modules -d lib --copy-files', {
+  stdio: 'inherit'
+})
+
+console.log('\nBuilding client bundles ...')
+
+execSync('webpack -p --json > stats.json', {
+  stdio: 'inherit',
+  env: Object.assign({}, process.env, {
+    NODE_ENV: 'production'
+  })
+})