Add CONFIG_SCHEMA to openstack provider
Add CONFIG_SCHEMA to openstack provider

SCHEMA_TEMPLATE was renamed to CONFIG_SCHEMA and moved to the class
scope.

Also, config validation was deleted from OpenStackProvider constructor
for using specified validation method in the base class.

Change-Id: Ia71d1858bd5a8b313e52188bfec3d95f100f5a8c
Related: blueprint common-config-validation

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