Add a link on Persona page to reset auth system

See https://github.com/marienfressinaud/FreshRSS/issues/521

app/i18n/en.php

@@ -5,6 +5,7 @@ return array (
 	'login'				=> 'Login',
 	'keep_logged_in'		=> 'Keep me logged in <small>(1 month)</small>',
 	'login_with_persona'		=> 'Login with Persona',
+	'login_persona_problem'		=> 'Problem of connection with Persona?',
 	'logout'			=> 'Logout',
 	'search'			=> 'Search words or #tags',
 	'search_short'			=> 'Search',

app/i18n/fr.php

@@ -5,6 +5,7 @@ return array (
 	'login'				=> 'Connexion',
 	'keep_logged_in'		=> 'Rester connecté <small>(1 mois)</small>',
 	'login_with_persona'		=> 'Connexion avec Persona',
+	'login_persona_problem'		=> 'Problème de connexion à Persona ?',
 	'logout'			=> 'Déconnexion',
 	'search'			=> 'Rechercher des mots ou des #tags',
 	'search_short'			=> 'Rechercher',

app/views/index/formLogin.phtml

@@ -29,8 +29,15 @@
 
 	case 'persona':
 		?><p>
-			<?php echo _i('login'); ?>
-			<a class="signin" href="#"><?php echo _t('login_with_persona'); ?></a>
+			<a class="signin btn btn-important" href="#">
+				<?php echo _i('login'); ?>
+				<?php echo _t('login_with_persona'); ?>
+			</a><br /><br />
+
+			<?php echo _i('help'); ?>
+			<small>
+				<a href="<?php echo _url('index', 'resetAuth'); ?>"><?php echo _t('login_persona_problem'); ?></a>
+			</small>
 		</p><?php
 		break;
 	} ?>