Switch to using oslo_* instead of oslo.*

The oslo team is recommending everyone to switch to the
non-namespaced versions of libraries. Updating the hacking
rule to include a check to prevent oslo.* import from
creeping back in.

This commit includes:
- using oslo_utils instead of oslo.utils
- using oslo_serialization instead of oslo.serialization
- using oslo_db instead of oslo.db
- using oslo_i18n instead of oslo.i18n
- using oslo_middleware instead of oslo.middleware
- using oslo_config instead of oslo.config
- using oslo_messaging instead of "from oslo import messaging"
- using oslo_vmware instead of oslo.vmware

Change-Id: I3e2eb147b321ce3e928817b62abcb7d023c5f13f

nova/tests/unit/api/ec2/test_cloud.py

@@ -27,8 +27,8 @@ import tempfile
 import fixtures
 import iso8601
 import mock
-from oslo.config import cfg
-from oslo.utils import timeutils
+from oslo_config import cfg
+from oslo_utils import timeutils
 
 from nova.api.ec2 import cloud
 from nova.api.ec2 import ec2utils