Vue Comments: Comments ported to Vue + DnD fileupload

* Drag and drop files to comment editor to add a file attachment
* Using Vue to render comments

Since comments now has attachments we need to update the schemas
./manage.py maintenance replace_pillar_node_type_schemas

src/scripts/js/es6/common/vuecomponents/user/Avatar.js

@@ -0,0 +1,12 @@
+const TEMPLATE = `
+<div class="user-avatar">
+    <img 
+        :src="user.gravatar"
+        :alt="user.full_name">
+</div>
+`;
+
+Vue.component('user-avatar', {
+    template: TEMPLATE,
+    props: {user: Object},
+});