perf:改进axios使用

src/main.js

 // The Vue build version to load with the `import` command
 // (runtime-only or standalone) has been set in webpack.base.conf with an alias.
 import Vue from 'vue'
-import App from './App'
 import VueRouter from 'vue-router'
+import axios from 'axios'
 import cookies from 'vue-cookies'
 import hljs from 'highlight.js'
 import useRouter from './router'
-import axios from 'axios'
+import App from './App'
 import importElementComponents from './importElement'
 import importEchartsComponents from './importEchartsComponents'