refactor:refine icons

src/router/index.js

     component: Layout,
     redirect: 'noredirect',
     name: 'Example',
-    icon: 'zujian',
+    icon: 'example',
     children: [
-      { path: 'index', name: 'Form', icon: 'zonghe', component: _import('page/form') }
+      { path: 'index', name: 'Form', icon: 'form', component: _import('page/form') }
     ]
   },
 
     path: '/table',
     component: Layout,
     redirect: '/table/index',
-    icon: 'tubiao',
+    icon: 'table',
     noDropdown: true,
     children: [{ path: 'index', name: 'Table', component: _import('table/index'), meta: { role: ['admin'] }}]
   },

src/views/login/index.vue

       <h3 class="title">vue-element-admin</h3>
       <el-form-item prop="username">
         <span class="svg-container svg-container_login">
-          <svg-icon icon-class="yonghuming" />
+          <svg-icon icon-class="user" />
         </span>
         <el-input name="username" type="text" v-model="loginForm.username" autoComplete="on" placeholder="username" />
       </el-form-item>
       <el-form-item prop="password">
         <span class="svg-container">
-          <svg-icon icon-class="mima"></svg-icon>
+          <svg-icon icon-class="password"></svg-icon>
         </span>
         <el-input name="password" type="password" @keyup.enter.native="handleLogin" v-model="loginForm.password" autoComplete="on"
           placeholder="password"></el-input>