Deleted unused template: `emails_change_successful.html`

lms/templates/emails_change_successful.html

-<%inherit file="main.html" />
-<%!
-from django.utils.translation import ugettext as _
-from django.core.urlresolvers import reverse
-%>
-
-<section class="container activation">
-
-  <section class="message">
-    <h1 class="invalid">${_("E-mail change successful!")}</h1>
-    <hr class="horizontal-divider">
-
-    <p>${_('You should see your new email in your {link_start}dashboard{link_end}.').format(
-        link_start='<a href="{url}">'.format(url=reverse('dashboard')),
-        link_end='</a>',
-      )}</p>
-  </section>
-</section>