FontAwesome v5.0.6 (#1372)

* Update FontAwesome to v5.0.6

* Adapt DiscussionListItem-count icon to match FontAwesome 5 syntax

* Change icon name to match FontAwesome 5.0.6 fas icon

* Add font type prefix parameter to icon helper

* Add Enable Icon Prefix to show icon in Extension Page

* Fix invalid icon behavior

* Change icon name to match FontAwesome 5.0.6 far icon

* Use iconPrefix property on component

* Use full icon class name

* Update icon helper docblock

* Full icon class syntax

js/forum/src/components/CommentPost.js

@@ -142,7 +142,7 @@ export default class CommentPost extends Post {
       items.add('toggle', (
         Button.component({
           className: 'Button Button--default Button--more',
-          icon: 'ellipsis-h',
+          icon: 'fa fa-ellipsis-h',
           onclick: this.toggleContent.bind(this)
         })
       ));