Upgrade Font Awesome to version 5 (#1446)

Upgrade Font Awesome to version 5 (SVG with JavaScript)

Close #1396

_includes/scripts.html

@@ -9,6 +9,7 @@
   {% endfor %}
 {% else %}
   <script src="{{ '/assets/js/main.min.js' | absolute_url }}"></script>
+  <script defer src="https://use.fontawesome.com/releases/v5.0.2/js/all.js"></script>
 {% endif %}
 
 {% if site.search == true or page.layout == "search" %}