Allow a well-known group (default 'xapi') to have read/write access to the xenopsd socket

This avoids having to run all the CLI commands as root with sudo.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
qemu: remove the 'interface' record in VIF_unplug

Signed-off-by: David Scott <dave.scott@eu.citrix.com>