Add handling for browsers without JavaScript

fixes #243

src/client/site/index.jade

@@ -22,8 +22,11 @@ html
             .view__header
 
             .content.hidden
-            .content-loading
+            script document.write('<div class="content-loading"><img src="/images/wait.gif"/></div>');
-                img(src="/images/wait.gif")
+
+            noscript
+                h1 Crafting Guide requires JavaScript to operate.
+                h1 Please re-enable JavaScript and reload the page.
 
             .view__footer
 

src/client/site/index.scss

@@ -67,6 +67,15 @@ html {
                 align-items     : center;
                 justify-content : center;
             }
+
+            > noscript {
+                margin: $size-margin-xlarge 0;
+                text-align: center;
+
+                h1 {
+                    font-size: $font-size-xlarge;
+                }
+            }
         }
     }
 }