Allow user to choose which columns to show, for Vue.js users grid

tailbone/templates/users/vue_index.mako

@@ -35,9 +35,6 @@
 
 </%def>
 
-## TODO: just, ugh.
-<br />
-
 <div id="vue-app">
   ## TODO: need to make endpoint a bit more configurable somehow
   <v-server-table name="users" url="/api/users" :columns="columns" :options="options">
@@ -92,6 +89,7 @@ var app = new Vue({
             'active'
         ],
         options: {
+            columnsDropdown: true,
             filterable: false,
             headings: {
                 person_display_name: "Person"