Stop importing print_function

We don't support Python 2.6 anymore so there is no use for that.

Change-Id: Ic1f8aefc4946752b03b25cac7a900f70c68133a5

ceilometer/tests/gabbi/fixtures.py

@@ -15,8 +15,6 @@
 
 """Fixtures used during Gabbi-based test runs."""
 
-from __future__ import print_function
-
 import datetime
 import os
 import random

doc/source/conf.py

@@ -10,7 +10,6 @@
 #
 # All configuration values have a default; values that are commented out
 # serve to show the default.
-from __future__ import print_function
 
 import sys
 import os

tools/make_test_data.py

@@ -24,8 +24,6 @@ source .tox/py27/bin/activate
 ./tools/make_test_data.py --user 1 --project 1 --resource 1 --counter cpu_util
 --volume 20
 """
-from __future__ import print_function
-
 import argparse
 import datetime
 import logging

tools/make_test_event_data.py

@@ -21,8 +21,6 @@ Generate testing data for e.g. for default time span
 source .tox/py27/bin/activate
 ./tools/make_test_event_data.py --event_types 3
 """
-from __future__ import print_function
-
 import argparse
 import datetime
 import logging

tools/show_data.py

@@ -13,8 +13,6 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.
-from __future__ import print_function
-
 import sys
 
 from oslo_config import cfg