Added two-factor resending to sign in flow.

Assumes user will have to get an admin to update phone number if lost.

app/templates/verification-not-received.html

@@ -0,0 +1,24 @@
+{% extends "admin_template.html" %}
+
+{% block page_title %}
+GOV.UK Notify
+{% endblock %}
+
+{% block content %}
+
+<div class="grid-row">
+  <div class="column-two-thirds">
+    <h1 class="heading-xlarge">Resend verification code</h1>
+
+    <p>Text messages sometimes take a few minutes to be received. <br> If you have not received a text message, you can resend.</p>
+
+    <p>If you no longer have access to your mobile phone and registered number, get in contact with your service manager to reset your number.</p>P>
+
+
+      <p>
+      <a class="button" href="two-factor" role="button">Resend confirmation code</a>
+      </p>
+  </div>
+</div>
+
+{% endblock %}