using hostvars and interface generic usage instead of hardcode

[kamihacker]

Hello there,

We could avoid using hard-coded interfaces such as:

https://github.com/xsuchy/openstack-ansible-install/blob/master/controler.yml#L37-L42

We could implement a check to figure out if the controller node uses fixed IP addresses or receives it from DHCP (like openstack instances sometimes do)

Also I guess we could also edit the "/etc/sysconfig/network-scripts/ifcfg-ethX" file depending on the server config, I am aware this is designed to fit Fedora Cloud but we could make it usable to other possible infrastructure, even Fedora Cloud might change the interface layout in the future