Switch all uses of httplib to import from six

As part of enabling python3 support in tempest we need to be able to
handle httplib usage in both python2 and python3. Six provides a compat
layer for doing this, so this commit moves all uses of httplib to get
it through six.

Change-Id: Ibf1d87908fe4004b37320439386abe5b1dc4bb51
diff --git a/tempest/common/glance_http.py b/tempest/common/glance_http.py
index fb5958c..5cd844c 100644
--- a/tempest/common/glance_http.py
+++ b/tempest/common/glance_http.py
@@ -17,7 +17,6 @@
 
 import copy
 import hashlib
-import httplib
 import json
 import posixpath
 import re
@@ -28,6 +27,7 @@
 from oslo_log import log as logging
 import six
 from six import moves
+from six.moves import http_client as httplib
 from six.moves.urllib import parse as urlparse
 from tempest_lib import exceptions as lib_exc
 
diff --git a/tempest/services/object_storage/object_client.py b/tempest/services/object_storage/object_client.py
index 0e02bbc..3466c8a 100644
--- a/tempest/services/object_storage/object_client.py
+++ b/tempest/services/object_storage/object_client.py
@@ -13,9 +13,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import httplib
 import urllib
 
+from six.moves import http_client as httplib
 from six.moves.urllib import parse as urlparse
 
 from tempest.common import service_client
diff --git a/tempest/tests/test_glance_http.py b/tempest/tests/test_glance_http.py
index 84b66d7..b132f60 100644
--- a/tempest/tests/test_glance_http.py
+++ b/tempest/tests/test_glance_http.py
@@ -13,13 +13,13 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import httplib
 import json
 import socket
 
 import mock
 from oslotest import mockpatch
 import six
+from six.moves import http_client as httplib
 from tempest_lib import exceptions as lib_exc
 
 from tempest.common import glance_http