Bug#644809: pulseaudio: Confusing warning

[Tony Houghton]

Isn't use of /etc/defaults to control whether a service is started by
an init script deprecated? I think it's preferred to use update-rc.d.
I think that would be a good way to fix this bug although I'm not sure
what policy says about init scripts which are disabled by default.
Probably best to show a message via dpkg when the package is first
installed or upgraded to a version which uses update-rc.d.