Authentication Settings: Add option to set password validity period

app/views/settings/_authentication.html.erb

@@ -31,6 +31,7 @@ See doc/COPYRIGHT.rdoc for more details.
                   [l("label_password_rule_#{r}"), r]
                 end %></p>
       <p><%= setting_text_field :password_min_adhered_rules, :size => 6 %></p>
+      <p><%= setting_text_field :password_days_valid, :size => 6 %></p>
       <p><%= setting_text_field :password_count_former_banned, :size => 6 %></p>
       <p><%= setting_check_box :lost_password, :label => :label_password_lost %></p>
     </fieldset>

config/locales/de.yml

@@ -1194,6 +1194,7 @@ de:
   setting_openid: "Erlaube OpenID-Anmeldung und -Registrierung"
   setting_password_active_rules: "Aktive Zeichenklassen"
   setting_password_count_former_banned: "Anzahl zuletzt benutzter Passwörter, die nicht wiederverwendet werden dürfen"
+  setting_password_days_valid: "Anzahl von Tagen, nach denen ein Passwortwechsel erwzwungen wird (deaktivieren mit 0)"
   setting_password_min_length: "Mindestlänge"
   setting_password_min_adhered_rules: "Mindestanzahl zu verwendender Zeichenklassen"
   setting_per_page_options: "Objekte pro Seite"

config/locales/en.yml

@@ -1174,6 +1174,7 @@ en:
   setting_openid: "Allow OpenID login and registration"
   setting_password_active_rules: "Active character classes"
   setting_password_count_former_banned: "Number of most recently used passwords banned for reuse"
+  setting_password_days_valid: "Number of days, after which to enforce a password change (disable with 0)"
   setting_password_min_length: "Minimum length"
   setting_password_min_adhered_rules: "Minimum number of required classes"
   setting_per_page_options: "Objects per page options"