fix(element): register element UI only once (#232)

Author: Pooya Parsa

template/frameworks/element-ui/plugins/element-ui.js

@@ -2,6 +2,4 @@ import Vue from 'vue'
 import Element from 'element-ui'
 import locale from 'element-ui/lib/locale/lang/en'
 
-export default () => {
-  Vue.use(Element, { locale })
-}
+Vue.use(Element, { locale })