Make send the send flow generic

This commit parameterises all methods in the send view so that they can send
either emails or SMS messages.

It works out what kind of message it is sending from the `template_type`
property of the template object.

This means that the `Template` util class needs to know about these properties,
which means that this commit depends on:
https://github.com/alphagov/notifications-utils/pull/2

This commit does _not_ add tests for sending emails. The existing tests for
sending SMS still pass, but actually sending emails is outside the scope of
this story.

app/templates/views/send.html

@@ -0,0 +1,43 @@
+{% extends "withnav_template.html" %}
+{% from "components/sms-message.html" import sms_message %}
+{% from "components/email-message.html" import email_message %}
+{% from "components/page-footer.html" import page_footer %}
+{% from "components/file-upload.html" import file_upload %}
+{% from "components/table.html" import list_table, field %}
+
+{% block page_title %}
+  Send text messages – GOV.UK Notify
+{% endblock %}
+
+{% block maincolumn_content %}
+
+  <h1 class="heading-large">Add recipients</h1>
+
+  <div class="grid-row">
+    <div class="column-two-thirds">
+      {% if 'sms' == template.template_type %}
+        {{ sms_message(template.formatted_as_markup) }}
+      {% elif 'email' == template.template_type %}
+        {{ email_message(
+          template.subject,
+          template.formatted_as_markup,
+          from_address='{}@notifications.service.gov.uk'.format(service.email_from),
+          from_name=service.name
+        ) }}
+      {% endif %}
+      {{ banner(
+        'You can upload real data, but we’ll only send to your mobile number until you <a href="{}">request to go live</a>'.format(
+          url_for('.service_request_to_go_live', service_id=service_id)
+        )|safe,
+        'info'
+      )}}
+    </div>
+  </div>
+
+  {{file_upload(form.file, button_text='Upload a CSV file')}}
+
+  <p>
+    <a href="{{ url_for('.get_example_csv', service_id=service_id, template_id=template.id) }}">Download an example CSV file</a>
+  </p>
+
+{% endblock %}