Revert "No longer use dhcp-hosts.conf to set static IP"

This reverts commit 131f2e69aed2541c7ed9a8be698129550052e4b2.

Setting static IP's using lxc.conf does not seem to work
well while the interface still also uses DHCP.  Instead we will
just use the dhcp-hosts.conf file to configure reserved DHCP IP
addresses.
Minor DHCP range change and documentation