Feature/english (#381)

* perf[navbar]: set langSelect to component && refine errorLog component

* feat[login]:add 18n to login form

* fix[pagination]: fixed when selected page-sizes

* perf[i18n]:dashboard document svg permission

* perf[charts]: perf effect

* perf[i18n]:excel && zip

* perf[i18n]: table && errorLog && theme

* perf[i18n]: components

* perf[i18n]: direct use $t

* perf[i18n]: complex-table

* update README.md

* update README.md 📘

* perf[i18n]: refine code comments

src/views/errorLog/index.vue

@@ -2,11 +2,13 @@
   <div class="errPage-container">
     <errorA></errorA>
     <errorB></errorB>
-
-    <h3>请点击右上角bug小图表</h3>
+    <!-- $t is vue-i18n global function to translate lang -->
+    <h3>{{$t('errorLog.tips')}}</h3>
     <code>
-      现在的管理后台基本都是spa的形式了，它增强了用户体验，但同时也会增加页面出问题的可能性，可能一个小小的疏忽就导致整个页面的死锁。好在 Vue 官网提供了一个方法来捕获处理异常.
-      <a target="_blank" class="link-type" href="https://panjiachen.github.io/vue-element-admin-site/#/error?id=%e4%bb%a3%e7%a0%81">文档介绍</a>
+      {{$t('errorLog.description')}}
+      <a target="_blank" class="link-type" href="https://panjiachen.github.io/vue-element-admin-site/#/error?id=%e4%bb%a3%e7%a0%81">
+        {{$t('errorLog.documentation')}}
+      </a>
     </code>
     <a href="#">
       <img src='https://wpimg.wallstcn.com/360e4842-4db5-42d0-b078-f9a84a825546.gif'>