Merge branch 'bugfix/134-img-fluid-banner' into 'develop'

Use img-fluid to scale bigger banner images automatically

Closes #134

See merge request hub/hub!368

src/backoffice/templates/backoffice/assembly_detail.html

@@ -72,7 +72,7 @@
       {% if assembly.banner_image %}
       <div class="card-header">{{ assembly.banner_image_width }}x{{ assembly.banner_image_height }}px</div>
       <div class="card-body">
-        <img src="{{ assembly.banner_image.url }}" alt="Banner Image">
+        <img src="{{ assembly.banner_image.url }}" alt="Banner Image" class="img-fluid">
       </div>
       {% else %}
       <div class="card-body">404 banner image :(</div>