use es6 syntax, use rollup build

bower.json

@@ -7,7 +7,6 @@
   "license": "MIT",
   "ignore": [
     ".*",
-    "build",
     "*.json",
     "*.md"
   ]

build.js

@@ -0,0 +1,61 @@
+var fs = require('fs');
+var rollup = require('rollup');
+var uglify = require('uglify-js');
+var babel = require('rollup-plugin-babel');
+var string = require('rollup-plugin-string');
+var package = require('./package.json');
+var version = process.env.VERSION || package.version;
+var banner =
+    "/*!\n" +
+    " * vue-form v" + version + "\n" +
+    " * Released under the MIT License.\n" +
+    " */\n";
+
+rollup.rollup({
+  entry: 'src/index.js',
+  plugins: [
+    string({ include: 'src/**/*.html' }),
+    babel({ presets: ['es2015-rollup'], plugins: ['transform-object-assign'] })
+  ]
+})
+.then(function (bundle) {
+  return write('dist/vue-form.js', bundle.generate({
+    format: 'umd',
+    banner: banner,
+    moduleName: 'VueForm'
+  }).code, bundle);
+})
+.then(function (bundle) {
+  return write('dist/vue-form.min.js',
+    banner + '\n' + uglify.minify('dist/vue-form.js').code,
+  bundle);
+})
+.then(function (bundle) {
+  return write('dist/vue-form.common.js', bundle.generate({
+    format: 'cjs',
+    banner: banner
+  }).code, bundle);
+})
+.catch(logError);
+
+function write(dest, code, bundle) {
+  return new Promise(function (resolve, reject) {
+    fs.writeFile(dest, code, function (err) {
+      if (err) return reject(err);
+      console.log(blue(dest) + ' ' + getSize(code));
+      resolve(bundle);
+    });
+  });
+}
+
+function getSize(code) {
+  return (code.length / 1024).toFixed(2) + 'kb';
+}
+
+function logError(e) {
+  console.log(e);
+}
+
+function blue(str) {
+  return '\x1b[1m\x1b[34m' + str + '\x1b[39m\x1b[22m';
+}