Put email address on team page

Right now, a user can change their name and masquerade as someone else
and the service manager has no way of telling who is who.

This is also true for platform admins, where they can see the users of
a service but can’t identify which department they are from.

This commit adds a user’s email address next to their name to remedy
this.

app/templates/views/manage-users.html

@@ -40,6 +40,8 @@ Manage users – GOV.UK Notify
           {{ user.name }}&ensp;<span class="hint">
             {%- if user.email_address == current_user.email_address -%}
               (you)
+            {% else %}
+              {{ user.email_address }}
             {% endif %}
           </span>
         </h3>