Cleanup py27 support

This repo is now testing only with Python 3, so let's make
a few cleanups:
- Remove python 2.7 stanza from setup.py
- Update requirements, no need for python_version anymore
- Use newer openstackdocstheme version
- Use hacking 3.0

Change-Id: Idefb3435a6b2b0765781fb6458c2def5a5e38a1d

doc/requirements.txt

@@ -1,5 +1,4 @@
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
-openstackdocstheme>=1.20.0  # Apache-2.0
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2 # BSD
+openstackdocstheme>=1.31.2  # Apache-2.0
 # releasenotes
 reno>=2.5.0 # Apache-2.0

setup.py

@@ -13,17 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr'],
     pbr=True)

test-requirements.txt

@@ -2,7 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-hacking>=2.0.0,<2.1.0 # Apache-2.0
+hacking>=3.0.0,<3.1.0 # Apache-2.0
 coverage>=4.0,!=4.4 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 stestr>=1.0.0 # Apache-2.0