Now all our scenarios should work with both keystone v2 and v3.
Also, this patch:
- sync both task files for keystone v2 and v3
- remove required_api_versions from
KeystoneBasic.authenticate_user_and_validate_token
- remove workarounds from cli tests for samples and certification task
Change-Id: I33f26b2da6905a4e62058a90a830e21de7c0fd8a