Allow primary keys to use different type than unicode.

Also return list of primary keys instead of a single unicode CSV value from
LDAPDelete-based commands.

This introduces a new capability 'primary_key_types' for backward
compatibility with old clients.

Reviewed-By: Tomas Babej <tbabej@redhat.com>

ipatests/test_xmlrpc/test_privilege_plugin.py

@@ -410,8 +410,8 @@ class test_privilege(Declarative):
             desc='Delete %r' % privilege1,
             command=('privilege_del', [privilege1], {}),
             expected=dict(
-                result=dict(failed=u''),
-                value=privilege1,
+                result=dict(failed=[]),
+                value=[privilege1],
                 summary=u'Deleted privilege "%s"' % privilege1,
             )
         ),