Add Apache 2.0 license to source file
Add Apache 2.0 license to source file

As per OpenStack licensing guide lines [1]:
[H102 H103] Newly contributed Source Code should be licensed under the Apache 2.0 license.

Change-Id: I66d3aef4d755845ce678af73af4ddfc9bc14495d

openstack/rally,openstack/rally,openstack/rally,yeming233/rally,openstack/rally,yeming233/rally