According to the latest agreement in Oslo team, apiclient and
clituils will be removed from Oslo incubator. We should keep
the local copy by ourselfs:
1. rename openstack/common/apiclient to common/apiclient
2. Because Ironic only use base.py and exception.py, so delete others.
3. rename openstack/common/cliutils.py to common/clituils.py
4. Delete openstack/common/_i18n becuase we have common/i18n.py
5. Delete openstack folder because it is empty
6. Add related unit tests and add oslotest to test-requirements.
Change-Id: I9eecd0457e86e82e65db1d0bc9a4c5c0ed4bbf74
