Convert english translation file

- convert english translation to translate key
- remove baggy template for login (never used since user isn't logged in and it'll use the default theme: material)
- fix tests about text in response (now checking translation key instead of translated text)
- remove all ugly `<div class="hidden">{{ form_rest(form) }}</div>`

src/Wallabag/UserBundle/Resources/views/TwoFactor/email_auth_code.html.twig

@@ -77,7 +77,7 @@
                         <td style="padding: 20px;" width="96px" valign="top"><img class="image_fix" src="{{ wallabag_url }}/themes/material/img/logo-other_themes.png" alt="logo" title="{{ wallabag_url }}" style="width: 96px; height: 96px;" /></td>
                         <td style="padding: 20px; padding-left: 0;" valign="top" id="cell_desc">
                             <h1>wallabag</h1>
-                            <h5>{% trans %}on{% endtrans %} {{ wallabag_url }}</h5>
+                            <h5>{{ "auth_code.on"|trans({}, 'wallabag_user') }} {{ wallabag_url }}</h5>
                         </td>
                     </tr>
                     <tr><td colspan="2" style="padding: 0;"><div style="height: 0; border-top: 1px solid #c5c5c5;">&nbsp;</div></td></tr>