支持SSR、升级Vue版本和增加新的icon (#40)

* search component add new style

* update vue version and support ssr

* unit test

* add new icon

* new icon

packages/tab/src/tabs.vue

@@ -7,6 +7,7 @@
       <div class="van-tabs__nav-bar" :style="navBarStyle" v-if="type === 'line'"></div>
       <div
         v-for="(tab, index) in tabs"
+        :key="index"
         class="van-tab"
         :class="{'van-tab--active': index === curActive}"
         ref="tabkey"