Put some statistics on the dashboard

This commit adds two new sections to the dashboard

1. A banner telling you about trial mode, including a count of how many messages
   you have left today, which is a restriction of trial mode

2. Panels with counts of how many emails and text messages have been sent in a
   day, plus the failure rates for each

It does **not**:
- link through to any further information about what trial mode is (coming
  later)
- link through to pages for the failure rates (coming later)
- change the ‘recent jobs’ section to ‘recent notifications’

app/templates/components/banner.html

@@ -1,19 +1,9 @@
 {% macro banner(body, type=None, with_tick=False, delete_button=None, subhead=None) %}
   <div class='banner{% if type %}-{{ type }}{% endif %}{% if with_tick %}-with-tick{% endif %}'>
-    {% if subhead %}
-      <div class="grid-row">
-        <div class="column-one-third">
-          {{ subhead }}
-        </div>
-        <div class="column-two-thirds">
-    {% endif %}
-
+    {% if subhead -%}
+        {{ subhead }}&ensp;
+    {%- endif -%}
     {{ body }}
-
-    {% if subhead %}
-        </div>
-      </div>
-    {% endif %}
     {% if delete_button %}
       <form method='post'>
         <input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />

app/templates/components/big-number.html

@@ -4,3 +4,14 @@
     <span class="big-number-label">{{ label }}</span>
   </div>
 {% endmacro %}
+
+
+{% macro big_number_with_status(number, label, status_number, status_label, percentage_bad=0) %}
+  <div class="big-number-with-status">
+    {{ big_number(number, label) }}
+    <div class="big-number-status">
+      <div class="big-number-status-error-percentage" style="opacity: {{ percentage_bad / 100 }}"></div>
+      {{ big_number(status_number, status_label) }}
+    </div>
+  </div>
+{% endmacro %}