Use Rollup and PostCSS for building

Author: fengyuanchen

.babelrc

@@ -0,0 +1,13 @@
+{
+  "presets": [
+    [
+      "es2015",
+      {
+        "modules": false
+      }
+    ]
+  ],
+  "plugins": [
+    "external-helpers"
+  ]
+}

.csscomb.json

@@ -0,0 +1,13 @@
+{
+  "extends": "airbnb-base",
+  "env": {
+    "browser": true
+  },
+  "rules": {
+    "arrow-body-style": 0,
+    "comma-dangle": 0,
+    "default-case": 0,
+    "no-param-reassign": 0,
+    "no-plusplus": 0
+  }
+}