Fix dev-quickstart.md - use pip to install openstack clients
Fix dev-quickstart.md - use pip to install openstack clients

Not all systems will have openstack clients in repositories.
The fixed guide suggest using pip to get up to date packages
via installing catch-all 'python-openstackclient'.

Change-Id: I5a84d944d51ede963f827737e917dd17e9466804

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