Fix header alignment.

Author: RubenVerborgh

default-templates/new-account/index.html

@@ -15,7 +15,7 @@
         <a href="/" class="navbar-brand">{{#if name}}{{name}} &ndash; {{/if}}Solid Home</a>
       </div>
       <div class="nav navbar-right navbar-form">
-        <button id="session-action" type="button" class="session-action btn btn-default navbar-btn">Loading...</button>
+        <button id="session-action" type="button" class="session-action btn btn-default">Loading...</button>
       </div>
     </div>
   </nav>