Use JavaScript Standard Style

Introduce JavaScript Standard Style as project style rule,
and fixed all fail on backend code.

package.json

@@ -5,7 +5,7 @@
   "main": "app.js",
   "license": "MIT",
   "scripts": {
-    "test": "npm run-script lint",
+    "test": "node ./node_modules/standard/bin/cmd.js && npm run-script lint",
     "lint": "eslint .",
     "dev": "webpack --config webpack.config.js --progress --colors --watch",
     "build": "webpack --config webpack.production.js --progress --colors",
@@ -165,8 +165,15 @@
     "optimize-css-assets-webpack-plugin": "^1.3.0",
     "script-loader": "^0.7.0",
     "style-loader": "^0.13.1",
+    "standard": "^9.0.1",
     "url-loader": "^0.5.7",
     "webpack": "^1.14.0",
     "webpack-parallel-uglify-plugin": "^0.2.0"
+  },
+  "standard": {
+    "ignore": [
+      "lib/ot",
+      "public/vendor"
+    ]
   }
 }