Description of problem:
IPA Web UI should have a feature to change non-posix group to posix group as cli can do with --posix option.

based onn email discussion (with Endi)> 
From Yi:
q2: if a non-posix user group being created, there is no way user
> > > can
> > > change it to posix group in WebUI. Currently, this is doable
> > > through
> > > CLI: "--posix" option. Is this is what we are intend to do
> > > (forbidden
> > > user change posix setting through UI) or this is a missing feature?
> 

From Endi
> I think this is a missing feature. We probably can add a link in the
> group details page that says "Change to a POSIX group". When clicked
> it
> will open a confirmation dialog with an optional field for the GID
> number. When you click Update it will execute group-mod and then
> refresh
> the details page. Now link will disappear and the GID field will
> become
> editable. What do you think?

From Yi
I don't like dialog box. It is hard to grab in ui automation. How about just a textfield for GID? once user click "Change to a POSIX group" (checkbox), a textfield appears next to it asking for GID. If no user input in GID textfield, GID will be automatic generated.