Caveat: I needed add an ifup call to the install-extras script,
because without it, the container wouldn't start the dhcp client
on the network. This fix feels wrong but seems to give at least
some improvement.
special config for centos 7 - for systemd...
The lxc-debian template aready does this, but apparently
the download template does not. We need to adapt the config
for installation as well as provide a version-specific config
for packaging the box.
