refactor: add eslint-plugin-vue && lint code (#976)

src/views/theme/index.vue

@@ -2,14 +2,14 @@
   <div class="app-container">
     <el-card class="box-card">
       <div slot="header">
-        <a class='link-type link-title' target="_blank" href='https://panjiachen.github.io/vue-element-admin-site/guide/advanced/theme.html'>
-        {{$t('theme.documentation')}}
+        <a class="link-type link-title" target="_blank" href="https://panjiachen.github.io/vue-element-admin-site/guide/advanced/theme.html">
+          {{ $t('theme.documentation') }}
         </a>
       </div>
       <div class="box-item">
-        <span class="field-label">{{$t('theme.change')}} : </span>
-        <el-switch v-model="theme"></el-switch>
-        <code style="margin-top:15px;">{{$t('theme.tips')}}</code>
+        <span class="field-label">{{ $t('theme.change') }} : </span>
+        <el-switch v-model="theme"/>
+        <code style="margin-top:15px;">{{ $t('theme.tips') }}</code>
       </div>
     </el-card>
 
@@ -22,19 +22,19 @@
     </div>
 
     <div class="block">
-      <el-button type="primary" icon="el-icon-edit"></el-button>
-      <el-button type="primary" icon="el-icon-share"></el-button>
-      <el-button type="primary" icon="el-icon-delete"></el-button>
+      <el-button type="primary" icon="el-icon-edit"/>
+      <el-button type="primary" icon="el-icon-share"/>
+      <el-button type="primary" icon="el-icon-delete"/>
       <el-button type="primary" icon="el-icon-search">Search</el-button>
       <el-button type="primary">
         Upload
-        <i class="el-icon-upload el-icon-right"></i>
+        <i class="el-icon-upload el-icon-right"/>
       </el-button>
     </div>
 
     <div class="block">
-      <el-tag class='tag-item' v-for="tag in tags" :type="tag.type" :key='tag.type'>
-        {{tag.name}}
+      <el-tag v-for="tag in tags" :type="tag.type" :key="tag.type" class="tag-item">
+        {{ tag.name }}
       </el-tag>
     </div>
 
@@ -47,7 +47,7 @@
     </div>
 
     <div class="block">
-      <el-slider v-model="slideValue"></el-slider>
+      <el-slider v-model="slideValue"/>
     </div>
 
   </div>
@@ -58,7 +58,7 @@ import { toggleClass } from '@/utils'
 import '@/assets/custom-theme/index.css' // the theme changed version element-ui css
 
 export default {
-  name: 'theme',
+  name: 'Theme',
   data() {
     return {
       theme: false,