upgrade to bootstrap 4, complete rewrite of template (#629)

_includes/footer-scripts.html

@@ -9,9 +9,9 @@
     <!-- doing something a bit funky here because I want to be careful not to include JQuery twice! -->
     {% if js contains 'jquery' %}
       <script>
-      	if (typeof jQuery == 'undefined') {
+        if (typeof jQuery == 'undefined') {
           document.write('<script src="{{ js | relative_url }}"></scr' + 'ipt>');
-      	}
+        }
       </script>
     {% else %}
       <script src="{{ js | relative_url }}"></script>