install Alpine.pm and configure its network

install Alpine.pm and configure its network

Since busybox' current default DHCPv6 client is unfinished
and alpine currently doesn't handle a 'dhcp' interface type
in its /etc/network/interfaces and bails out when
configuring the network with a broken config we have to make
sure we don't pass this on to debian's setup_network.

Unfortunately a warning at this point would only be visible
when creating a container because at this point no warning
makes it to the console/UI (and errors would be hidden
because the setup runs in our lxc prestart hook).