vuecli按需引入element ui方式（包括几个特殊的使用如message，loading）

　　为了减小项目体积的目的，所以使用按需引入。

import { Loading, Select, Option, Input, Form, FormItem, Upload, Image, MessageBox, Message, Pagination, Table, TableColumn, Dialog } from 'element-ui'

Vue.component(Select.name, Select);
Vue.component(Option.name, Option);
Vue.component(Input.name, Input);
Vue.component(Form.name, Form);
Vue.component(FormItem.name, FormItem);
Vue.component(Upload.name, Upload);
Vue.component(Image.name, Image);
Vue.component(MessageBox.name, MessageBox);
Vue.component(Message.name, Message);
Vue.component(Pagination.name, Pagination);
Vue.component(Table.name, Table);
Vue.component(TableColumn.name, TableColumn);
Vue.component(Dialog.name, Dialog);

Vue.use(Vuex)
Vue.prototype.$loading = Loading.service;
Vue.prototype.$confirm = MessageBox.confirm;
Vue.prototype.$alert = MessageBox.alert;
Vue.prototype.$message = Message;