dependency scaner for webpack generated code

use astw-babylon as ast parser and walker, collect require()'s param, which is dependency of current file.

accept three arguments: file(gulp Vinyl对象), dependencies(空对象, 做引用传递), options(编译配置)

returns nothing, but modify dependencies object to 对象结构: { requires: [depA, depB] }

push vue-lib, vue-render for vue generated web code. vue-patch not handled yet.

功能

• 通过ast walk, 解析define/require中声明的单个/多个依赖
• 针对非Literal String的依赖报警, 变量依赖会导致在native端无法运行
• 给web代码添加weex三端代码统一三件套的依赖: vuejs/runtime, vuejs/render, weex-vue-patch/index
• 忽略vue-loader打包web代码时生成的vue, vue-loader, css-loader的冗余依赖