Fix 500 when saving /site/edit without email
When saving /site/edit with no no_reply_email set, a 500 error page
would be returned due to an empty value being passed as value to
the datastore (which is not allowed for email fields).
{% ifnotequal prev_start -1 %}<a href="{{ start_base_url }}&start={{ prev_start }}">‹ Previous</a>{% endifnotequal %}
{% for page in pages %}
<a {% ifequal page.number current_page %} class="ae-page-selected ae-page-number" {% endifequal %}
href="{{ start_base_url }}&start={{ page.start }}">{{ page.number }}</a>
{% endfor %}
{% ifnotequal next_start -1 %}<a href="{{ start_base_url }}&start={{ next_start }}">Next ›</a>{% endifnotequal %}