Drop use of 'oslo' namespace package

The Oslo libraries have moved all of their code out of the 'oslo'
namespace package into per-library packages. The namespace package was
retained during kilo for backwards compatibility, but will be removed by
the liberty-2 milestone. This change removes the use of the namespace
package, replacing it with the new package names.

The patches in the libraries will be put on hold until application
patches have landed, or L2, whichever comes first. At that point, new
versions of the libraries without namespace packages will be released as
a major version update.

Please merge this patch, or an equivalent, before L2 to avoid problems
with those library releases.

Blueprint: remove-namespace-packages
https://blueprints.launchpad.net/oslo-incubator/+spec/remove-namespace-packages

Change-Id: Iaf9247f90ba26615d02e5431d6bc98f22351caa7

oslo_db/sqlalchemy/session.py

@@ -23,7 +23,7 @@ Recommended ways to use sessions within this framework:
 
   .. code-block:: python
 
-    from oslo.db.sqlalchemy import enginefacade
+    from oslo_db.sqlalchemy import enginefacade
 
     @enginefacade.reader
     def get_foo(context, foo):

oslo_db/sqlalchemy/test_base.py

@@ -234,7 +234,7 @@ def optimize_db_test_loader(file_):
     Place this in an __init__.py package file within the root of the test
     suite, at the level where testresources loads it as a package::
 
-        from oslo.db.sqlalchemy import test_base
+        from oslo_db.sqlalchemy import test_base
 
         load_tests = test_base.optimize_db_test_loader(__file__)
 

oslo_db/tests/old_import_api/sqlalchemy/test_options.py

@@ -11,8 +11,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from oslo.config import cfg
-from oslo.config import fixture as config
+from oslo_config import cfg
+from oslo_config import fixture as config
 
 from oslo.db import options
 from oslo_db.tests.old_import_api import utils as test_utils

oslo_db/tests/old_import_api/sqlalchemy/test_sqlalchemy.py

@@ -21,7 +21,7 @@ import logging
 
 import fixtures
 import mock
-from oslo.config import cfg
+from oslo_config import cfg
 from oslotest import base as oslo_test
 import sqlalchemy
 from sqlalchemy import Column, MetaData, Table

oslo_db/tests/old_import_api/test_api.py

@@ -16,8 +16,8 @@
 """Unit tests for DB API."""
 
 import mock
-from oslo.config import cfg
-from oslo.utils import importutils
+from oslo_config import cfg
+from oslo_utils import importutils
 
 from oslo.db import api
 from oslo.db import exception

oslo_db/tests/old_import_api/utils.py

@@ -15,7 +15,7 @@
 
 import contextlib
 
-from oslo.config import cfg
+from oslo_config import cfg
 from oslotest import base as test_base
 from oslotest import moxstubout
 import six