[Feature] Can reorder columns

Author: gurghet

dist/static/vue-smart-table-default.css

@@ -14,8 +14,9 @@
     :auto-load="true"
     body-field="results"
     id-col="id.value"
-    endpoint="http://api.randomuser.me/?page=1&results=20"
+    endpoint="http://api.randomuser.me/?page=1&results=20&seed=abc"
     :header="{'name.first': 'name', 'name.last': 'surname', gender: 'gender', 'phone+cell': 'contacts', 'picture.thumbnail': 'avatar', nat: 'nationality'}"
+    :order-by="['name.first', 'name.last']"
     >
    <src2img slot="picture.thumbnail"></src2img>
    <!-- this component will read the image