Add new platform admin page

Added a new platform admin page, at '/plaform-admin-new' which shows
different data. This no longer offers the option to filter by test-key,
only by date, and also gives a more detailed break-down of the
notifications and failures sent with a normal / research key.

The existing platform admin stats page ('/platform-admin') has not been
deleted yet so that both pages can be compared.

app/templates/components/status-box.html

@@ -0,0 +1,15 @@
+{% macro status_box(number, label, failing=false, percentage=None, url=None) %}
+  <div class="big-number-with-status">
+    <div class="big-number-status{% if failing %}-failing{% endif %}">
+      {% if url %}
+        <a href="{{ url }}">{{ number }} {{ label }}</a>
+      {% else %}
+        {{ number }} {{ label }}
+      {% endif %}
+
+      {% if percentage %}
+        - {{ percentage }}%
+      {% endif %}
+    </div>
+  </div>
+{% endmacro %}