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/virt/block_device.py

@@ -15,8 +15,8 @@
 import functools
 import operator
 
-from oslo.serialization import jsonutils
-from oslo.utils import excutils
+from oslo_serialization import jsonutils
+from oslo_utils import excutils
 
 from nova import block_device
 from nova.i18n import _