Refactor the web app bootstrapping code

- All custom JS variables are now preloaded into the `app.data` object, rather than directly on the `app` object. This means that admin settings are available in `app.data.settings` rather than `app.settings`, etc.
- Cleaner route handler generation
- Renamed ConfigureClientView to ConfigureWebApp, though the former still exists and is deprecated
- Partial fix for #881 (strips ?nojs=1 from URL if possible, so that refreshing will attempt to load JS version again)

views/content.blade.php

@@ -2,16 +2,22 @@
   {{ $translator->trans('core.views.content.loading_text') }}
 </div>
 
-@if (! $noJs) <noscript> @endif
-<div class="Alert">
-  <div class="container">
-    @if ($noJs)
-      {{ $translator->trans('core.views.content.load_error_message') }}
-    @else
-      {{ $translator->trans('core.views.content.javascript_disabled_message') }}
-    @endif
-  </div>
-</div>
+@if ($allowJs)
+  <noscript>
+    <div class="Alert">
+      <div class="container">
+        {{ $translator->trans('core.views.content.javascript_disabled_message') }}
+      </div>
+    </div>
 
-{!! $content !!}
-@if (! $noJs) </noscript> @endif
+    {!! $content !!}
+  </noscript>
+@else
+  <div class="Alert Alert--error">
+    <div class="container">
+      {{ $translator->trans('core.views.content.load_error_message') }}
+    </div>
+  </div>
+
+  {!! $content !!}
+@endif