Replace utils.ensure_(str|unicode) with strutils.safe(decode|encode)

Glanceclient implemented both functions before they landed into oslo.
Since both functions are already in oslo, it is now possible to pull
them in.

There's a small difference between glance's implementation and oslo's,
that is the later does not convert non-str objects - int, bool - to str
before trying to decode / encode them. This patch takes care of that
where necessary, more precisely, while encoding headers before doing a
new request.

Fixes bug: #1172253

Change-Id: I9a0dca31140bae28d8ec6aede515c5bb852b701b

glanceclient/v2/images.py

@@ -16,6 +16,7 @@
 import urllib
 
 from glanceclient.common import utils
+from glanceclient.openstack.common import strutils
 
 DEFAULT_PAGE_SIZE = 20
 
@@ -52,7 +53,7 @@ class Controller(object):
 
         for param, value in filters.iteritems():
             if isinstance(value, basestring):
-                filters[param] = utils.ensure_str(value)
+                filters[param] = strutils.safe_encode(value)
 
         url = '/v2/images?%s' % urllib.urlencode(filters)