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: I52848a1f63cb4a1b30d9e1c32f4bb18c5d9fe80e

castellan/openstack/common/_i18n.py

@@ -17,14 +17,14 @@ See http://docs.openstack.org/developer/oslo.i18n/usage.html
 """
 
 try:
-    import oslo.i18n
+    import oslo_i18n
 
     # NOTE(dhellmann): This reference to o-s-l-o will be replaced by the
     # application name when this module is synced into the separate
     # repository. It is OK to have more than one translation function
     # using the same domain, since there will still only be one message
     # catalog.
-    _translators = oslo.i18n.TranslatorFactory(domain='castellan')
+    _translators = oslo_i18n.TranslatorFactory(domain='castellan')
 
     # The primary translation function using the well-known name "_"
     _ = _translators.primary

castellan/openstack/common/fileutils.py

@@ -20,7 +20,7 @@ import os
 import stat
 import tempfile
 
-from oslo.utils import excutils
+from oslo_utils import excutils
 
 LOG = logging.getLogger(__name__)