Conditionally add dhcp-all-interfaces

If the /etc/init drectory gets created on Fedora, it causes
os-svc-daemon to add upstart init scripts instead of systemd.
As a result none of the openstack services can start.

Partial-Bug: #1239880

Change-Id: Iec317baa3eb9ff651fa66c582d2f614993cde45e