Show a tour when users first create a service

This commit adds a 3 screen tour, similar to those used on GOV.UK Verify
and Passports.

We guerilla tested this on Friday, and it really helped users to build a
mental model of how Notify works, so that when they’re playing around
with it they have a greater sense of what they’re aiming to do. This
makes concepts like templates and placeholders click more quickly.

https://www.pivotaltracker.com/story/show/116710119

app/templates/views/tour/3.html

@@ -0,0 +1,32 @@
+{% extends "withoutnav_template.html" %}
+{% from "components/textbox.html" import textbox %}
+{% from "components/page-footer.html" import page_footer %}
+{% from "components/banner.html" import banner_wrapper %}
+
+{% block page_title %}
+  {{heading}} – GOV.UK Notify
+{% endblock %}
+
+{% block maincolumn_content %}
+
+  {% call banner_wrapper(type='tour') %}
+	<h2 class="heading-large">Add recipients</h2>
+	<p>
+		Add recipients by uploading a .csv spreadsheet:
+	</p>
+	<p>
+		<img
+			src="/static/images/tour/{{ current_page }}.png"
+			width="554" height="118"
+			alt="A screenshot of a spreadsheet containing data about three people"
+		>
+	</p>
+	<p>
+		Developers, you can add data automatically using an API
+	</p>
+    <a href='{{ url_for('.tour', service_id=service_id, page=next_page) }}'>
+      Next
+    </a>
+  {% endcall %}
+
+{% endblock %}