[Pkg-samba-maint] Bug#672497: Bug#672497: full support for usershares (public shares)

[email.bug at arcor.de]

> samba package settings to diverge from upstream defaults

I understand that the usershares option was already a deviation from
the upstream default, to enable usershares. The public share options
might just have been forgotten at that time.

BTW for ad-hock shares II prefer public shares, because it does not
require to enter my valid userdata into unknown computers.

(I found the owner only option I mentioned is already the upstream default,
so no change there.)