Add ability to stage multiple users

Add 'Stage' button on  search page where preserved users are listed.

https://fedorahosted.org/freeipa/ticket/5371

Reviewed-By: Petr Vobornik <pvoborni@redhat.com>

ipaserver/plugins/internal.py

@@ -225,6 +225,7 @@ class i18n_messages(Command):
             "save": _("Save"),
             "set": _("Set"),
             "show": _("Show"),
+            "stage": _("Stage"),
             "unapply": ("Un-apply"),
             "update": _("Update"),
             "view": _("View"),
@@ -684,6 +685,8 @@ class i18n_messages(Command):
                 "activate_success": _("${count} user(s) activated"),
                 "label": _("Stage users"),
                 "preserved_label": _("Preserved users"),
+                "stage_confirm": _("Are you sure you want to stage selected users?"),
+                "stage_success": _("${count} users(s) staged"),
                 "undel_confirm": _("Are you sure you want to restore selected users?"),
                 "undel_success": _("${count} user(s) restored"),
                 "user_categories": _("User categories"),