upgrade version 2.0,add login api,upgrade api verison,add document and unit test

router/login.js

@@ -0,0 +1,34 @@
+const express = require("express")
+const crypto = require('crypto')
+const router = express()
+const { createWebAPIRequest } = require("../util/util")
+
+router.get("/", (req, res) => {
+  const email = req.query.email
+  const cookie = req.get('Cookie') ? req.get('Cookie') : ''
+  const md5sum = crypto.createHash('md5')
+  md5sum.update(req.query.password)
+  const data = {
+    'username': email,
+    'password': md5sum.digest('hex'),
+    'rememberLogin': 'true'
+  }
+
+  createWebAPIRequest(
+    'music.163.com',
+    '/weapi/login',
+    'POST',
+    data,
+    cookie,
+    (music_req, cookie) => {
+      console.log(music_req)
+      res.set({
+        'Set-Cookie': cookie,
+      })
+      res.send(music_req)
+    },
+    err => res.status(502).send('fetch error')
+  )
+})
+
+module.exports = router