Rework ranges of the nova_fixed network

The "router" range is not really needed since the switch to neutron. Neutron
can allocate the IP addresses for the router ports automatically.
Remove "dhcp" range from "public" network

It's not used anywhere anymore. Additionally enhance the "host" range to
include all the addresses that where part of the "dhcp" range before.
Enhance the "host" range of nova_floating

Turn it into a /25 subnet and make it possible to use all addresses of that.
Merge pull request #287 from rhafer/ranges-cleanup

cleanup up default network ranges