GID field should be enabled by default since the default group is posix.
Was caused by option_widget_base not properly reporting value change while
selecting the default value. It has to be notified with delay otherwise the
event is consumed by FieldBinder.
https://fedorahosted.org/freeipa/ticket/4325
Reviewed-By: Endi Sukma Dewata <edewata@redhat.com>
Tests modified to comply with PEP8 rules with exception of rule E501 (long lines).
Done by autopep8 tool and 2 manual modifications.
https://fedorahosted.org/freeipa/ticket/3744
