SSSD info plugin is immutable if not preconfigured

SSSD info plugin is immutable if not preconfigured

The SSSD info plugin configures SSSD and modules in
Apache as root during installation. This cannot be
done in the UI so we must not allow users to modify
the state if it was not "preconfigured" during
install.

If it has been configured then users are allowed
to enable/disable the plugin.

This is controlled by a value stored in the
info_config table, preconfigured.

The plugin configuration is hidden from the UI by
overridding the get_config_object() method.

https://fedorahosted.org/ipsilon/ticket/111

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-by: Rob Crittenden <rcritten@redhat.com>