2015 survey: replace redirection by a small page

content/2015-survey.rst

+Kwant user survey
+=================
+
+The kwant user survey is finished, please use the `mailing list
+</community.html>`_ if you would like to leave feedback.

htaccess-apache

@@ -30,7 +30,6 @@ RewriteRule ^(.*[^/])$ /$1.html [L]
 RewriteCond %{REQUEST_FILENAME} !-d
 RewriteRule ^(.*)/$  /$1 [R=301,L]
 
-Redirect 302 /2015-survey https://docs.google.com/forms/d/1j0LiFdZLjvfwoEyg5FML6z3sFKqV3Ar1mWReonYhatA/viewform
 Redirect 302 /contact /authors
 Redirect 302 /citing /cite
 Redirect 302 /download /install