adjust search so that it works for non-admin users
Non-admin user can now search for:
- hosts
- hostgroups
- netgroups
- servers
- services
(Fixes ACI issue where search returns nothing when user does't have
read rights for an attribute in search_attributes.
https://fedorahosted.org/freeipa/ticket/5167
Reviewed-By: Tomas Babej <tbabej@redhat.com>