In 'Expert Settings' page add new 'Allowed group(s)' field. (fate #312146)

To facilitate populating the requires_of_membership field in
pam_winbind.conf configuration file we add a new 'Allowed group(s)' field.

Signed-off-by: Noel Power <noel.power@suse.com>
update version & update Changelog info
Merge pull request #15 from noelpower/membership_of_fate#312146

In 'Expert Settings' page add new 'Allowed group(s)' field. (fate #31214...
Merge with upstream