In case Orca looses access to BrlAPI

Hello,

I don't know why but Orca had lost its access to BrlAPI.

I think this goes thourhg pollkit for years now, so the following fix
may very well be nothing more thand a dirty workaround, but at least it
works.

I created a brraille system group on my machine, made /etc/brlapi.key
belong to that group and added my user as well as thelightdm user to
that group.

That way I have braille both before and after login.

Seb.