[Pkg-samba-maint] sambashare group and enabling usershares by default

[Michael Tokarev]

In debian, samba package carries a patch which enables user shares
by default. I don't know why this was made this way, - usershares
are an additional potential for security issues, and they're not
actually as widely used.  We have to explicitly disable then
(usershare max shares = 0) on every samba install.

I'd love to get rid of this change. This warrants a NEWS entry
ofcourse, because this has a high potential for breaking users
config. This is not a problem per se.

There's also an interesting twist about sambashare group and
the default path for usershares set to /var/lib/samba/usershares/ -
this group and this directory are created on every upgrade of
the samba package, even if the administrator explicitly removed
them before. I think this should be guarded with !upgrade.

What do you think?

Thanks,

/mjt