use a single controller for all routes, with meaningful names

templates/web/renater/validate_challenge.html.tt2

 [% WRAPPER index.html.tt2 %]
-<form class="wizard clearfix" action="[% c.url_for('step4') %]" method="get">
+<form class="wizard clearfix" action="[% c.url_for('show_accounts_html') %]" method="get">
     <div class="steps clearfix">
         <ol>
             <li class="done">[% c.loc("Select your service provider") %]</li>