Merge pull request #1270 from OpenTechFund/fix/e-mail-base-template

Empty line after salutation and correct signature divider.

opentech/apply/activity/templates/messages/email/base.html

 {% block salutation %}Dear {{ user }},{% endblock %}
+
 {% block content %}{% endblock %}
 {% block more_info %}{% endblock %}
 Kind Regards,
 The OTF Team
 
---
+-- 
 Open Technology Fund
 https://www.opentech.fund/
 {% block post_signature_content %}{% endblock %}