[Improvement] eslint before build (#455)

package.json

@@ -20,6 +20,7 @@
     "deploy:cdn": "superman cdn /zanui/vant docs/dist/*.js docs/dist/*.css && superman cdn /zanui/vant/async_en-US docs/dist/async_en-US/*.js && superman cdn /zanui/vant/async_zh-CN docs/dist/async_zh-CN/*.js",
     "deploy:docs": "rimraf docs/dist && cross-env NODE_ENV=production webpack --progress --hide-modules --config  build/webpack.config.prod.js",
     "dist": "node build/bin/build-lib.js",
+    "lint": "./node_modules/.bin/eslint ./packages --ext .js --ext .vue",
     "test": "karma start test/unit/karma.conf.js --single-run",
     "test:coverage": "open test/unit/coverage/lcov-report/index.html",
     "test:watch": "karma start test/unit/karma.conf.js",
@@ -56,6 +57,7 @@
     "cross-env": "^5.1.1",
     "css-loader": "^0.28.7",
     "dependency-tree": "^5.12.0",
+    "eslint": "^4.13.1",
     "eslint-plugin-vue": "^2.1.0",
     "extract-text-webpack-plugin": "3.0.2",
     "fast-vue-md-loader": "^1.0.3",
@@ -79,6 +81,7 @@
     "precss": "2.0.0",
     "progress-bar-webpack-plugin": "^1.10.0",
     "rimraf": "^2.5.4",
+    "shelljs": "^0.7.8",
     "sinon": "^2.4.1",
     "sinon-chai": "^2.12.0",
     "style-loader": "^0.19.1",