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/views/dashboard/dashboard.html

@@ -0,0 +1,20 @@
+{% extends "withnav_template.html" %}
+
+{% block page_title %}
+  {{ session.get('service_name', 'Dashboard') }} – GOV.UK Notify
+{% endblock %}
+
+{% block maincolumn_content %}
+
+  {% if service.restricted %}
+    {% include 'views/dashboard/trial-mode-banner.html' %}
+  {% endif %}
+
+  {% if not jobs %}
+    {% include 'views/dashboard/get-started.html' %}
+  {% else %}
+    {% include 'views/dashboard/today.html' %}
+    {% include 'views/dashboard/jobs.html' %}
+  {% endif %}
+
+{% endblock %}