Add the ability to specify versions for clients
Add the ability to specify versions for clients

Adds new parameter 'version' to 'clients' and 'admin_clients'
methods from base Scenario class, which allows to state
a particular version to the various OpenStack clients.

Change-Id: I4b1abd1faa9f682ef920f815525fcc4ce4a41c1d

paboldin/rally,paboldin/rally,gluke77/rally,group-policy/rally,gluke77/rally,vponomaryov/rally,vefimova/rally,amit0701/rally,pyKun/rally,openstack/rally,vganapath/rally,pyKun/rally,paboldin/rally,vponomaryov/rally,cernops/rally,shdowofdeath/rally,vefimova/rally,openstack/rally,group-policy/rally,gluke77/rally,amit0701/rally,pandeyop/rally,eonpatapon/rally,redhat-openstack/rally,pandeyop/rally,vganapath/rally,aplanas/rally,aplanas/rally,cernops/rally,varunarya10/rally,eayunstack/rally,eonpatapon/rally,openstack/rally,afaheem88/rally,yeming233/rally,shdowofdeath/rally,go-bears/rally,aforalee/RRally,vganapath/rally,group-policy/rally,eayunstack/rally,aforalee/RRally,vganapath/rally,amit0701/rally,eayunstack/rally,redhat-openstack/rally,afaheem88/rally,yeming233/rally,go-bears/rally,openstack/rally,varunarya10/rally,gluke77/rally