fix subnet-create call for demo-net
fix subnet-create call for demo-net

(neutron client version: 2.5.0)

The option is --dns-nameservers not --dns_namservers and the
subnet-create subcommand expects the NETWORK and CIDR to be adjacent
args.

Change-Id: I4f776632902fd001c38ee5c8c87a213883ca87be

tonyli71/kolla,brk3/kolla,jakedahn/kolla,fdumpling/kolla,intel-onp/kolla,mrangana/kolla,mrangana/kolla,chenzhiwei/kolla,toby82/kolla,jakedahn/kolla,dardelean/kolla-ansible,stackforge/kolla,rajalokan/kolla,GalenMa/kolla,HackToday/kolla,chenzhiwei/kolla,LoHChina/kolla,limamauricio/mykolla,chenzhiwei/kolla,toby82/kolla,negronjl/kolla,coolsvap/kolla,mandre/kolla,openstack/kolla,rahulunair/kolla,nihilifer/kolla,rajalokan/kolla,nihilifer/kolla,GalenMa/kolla,HackToday/kolla,coolsvap/kolla,tonyli71/kolla,coolsvap/kolla,toby82/kolla,negronjl/kolla,LoHChina/kolla,openstack/kolla,intel-onp/kolla,mandre/kolla,stackforge/kolla,negronjl/kolla,rajalokan/kolla,meticulo3366/kolla,mandre/kolla,rahulunair/kolla,limamauricio/mykolla,limamauricio/mykolla,invenfantasy/kolla,invenfantasy/kolla,meticulo3366/kolla,fdumpling/kolla,LoHChina/kolla,stackforge/kolla,fdumpling/kolla,brk3/kolla,jakedahn/kolla,dardelean/kolla-ansible,dardelean/kolla-ansible,HackToday/kolla,invenfantasy/kolla