Fix for address allocation respecting existing libvirt networks
Fix for address allocation respecting existing libvirt networks

listDefinedNetworks() show only stopped networks, skipping 'active'
networks.
To get all libvirt networks, let's use listAllNetworks()

Change-Id: Id86496af007dbb28ce78bfd239b30fba36cc39cf

stackforge/fuel-devops,stackforge/fuel-devops