Add basic flow for adding email _or_ sms templates

Templates now have:
- a type (email or sms)
- a subject (if they are email templates)

We don’t want two completely separate view files for email and SMS, because they
would have an enormous amount of repetition.

So this commit adds
- different templates for SMS and email templates
- different form objects for SMS and email templates

…and wires them up.

app/main/views/index.py

@@ -22,15 +22,3 @@ def register_from_invite():
 @login_required
 def verify_mobile():
     return render_template('views/verify-mobile.html')
-
-
-@main.route("/services/<service_id>/send-email")
-@login_required
-def send_email(service_id):
-    return render_template('views/send-email.html', service_id=service_id)
-
-
-@main.route("/services/<service_id>/check-email")
-@login_required
-def check_email(service_id):
-    return render_template('views/check-email.html')