bump oslo.config req to 1.2.0a3
bump oslo.config req to 1.2.0a3

bump up oslo.config requirement to 1.2.0.a3 so it doesn't pull in
older oslo.config on pip install --upgrade

Change-Id: I121ef939fd3b768e15adf6abf95cf0a1899c71b5

varunarya10/pycadf,citrix-openstack-build/pycadf