start to work in requests by cleaning up listing code

_includes/listings.njk

@@ -0,0 +1,19 @@
+{% set tag = "offers" %}
+
+<div id="listings">
+  {% for tag in collections | getKeys | removeCoreTags | sortAlphabetically %}
+    <div class="category">
+      <div class="category-title">
+        <h2>{{ tag }}</h2>
+        <p>{{ tag | getTagline }}</p>
+      </div>
+      {% set listings = collections[tag] | filterByDate(day) | filterByTag(tag) %}
+      {% if listings | length == 0 %}
+      <p>No listings.</p>
+      {% endif %}
+      {% for listing in listings | sortAlphabeticallyByTitle %}
+        {% include "listing.njk" %}
+      {% endfor %}
+    </div>
+  {% endfor %}
+</div>