Change oslo.utils to oslo_utils

The oslo.utils libraries are moving away from namespace packages.

This requires oslo.utils>=1.2.0

bp drop-namespace-packages

Change-Id: I803df61e91eabb96329d859aef6bea03530fb84f

glanceclient/v2/images.py

@@ -15,7 +15,7 @@
 
 import json
 
-from oslo.utils import encodeutils
+from oslo_utils import encodeutils
 import six
 from six.moves.urllib import parse
 import warlock