Client: semantic ui -> bootstrap 4 and less -> scss (#8535)

* client: semantic ui -> bootstrap 4 and less -> scss

* start porting components to boostrap

* port header, start porting menu

* port loading screen

* port most of the menu

* port secondary menus

* port guilds and stable

* disable tavern for now, port inbox

* typo

* put back old tavern code

website/client/components/userTasks.vue

@@ -1,6 +1,6 @@
 <template lang="pug">
 .row
-  .four.wide.column(v-for="taskType in tasksTypes")
+  .col(v-for="taskType in tasksTypes")
     h3 {{taskType}}s
     ul
       task(v-for="task in tasks", v-if="task.type === taskType", :key="task.id", :task="task")