Cleanup py27 support

Make a few cleanups:
- Remove python 2.7 stanza from setup.py
- Add requires on python >= 3.6 to setup.cfg so that pypi and pip
  know about the requirement
- Remove obsolete sections from setup.cfg:
  * Wheel is not needed for python 3 only repo
- Update classifiers
- Update requirements, no need for python_version anymore

Change-Id: I705a40cb3a19e16641a2b9de6891ab72fe2b98f0

doc/requirements.txt

@@ -4,6 +4,5 @@
 openstackdocstheme>=1.20.0 # Apache-2.0
 osprofiler>=1.4.0 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
-sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
+sphinx>=1.8.0,!=2.1.0 # BSD
 reno>=2.5.0 # Apache-2.0

lower-constraints.txt

@@ -26,7 +26,6 @@ docker==2.4.2
 docutils==0.14
 dogpile.cache==0.6.5
 dulwich==0.19.0
-enum34==1.0.4
 enum-compat==0.0.2
 eventlet==0.18.2
 extras==1.0.0

requirements.txt

@@ -14,7 +14,6 @@ alembic>=0.8.10 # MIT
 cliff!=2.9.0,>=2.8.0 # Apache-2.0
 decorator>=3.4.0 # BSD
 docker>=2.4.2 # Apache-2.0
-enum34>=1.0.4;python_version=='2.7' or python_version=='2.6' or python_version=='3.3' # BSD
 eventlet!=0.18.3,!=0.20.1,>=0.18.2 # MIT
 iso8601>=0.1.11 # MIT
 jsonpatch!=1.20,>=1.16 # BSD

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-dev@lists.openstack.org
 home-page = http://docs.openstack.org/magnum/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,6 +14,8 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -76,10 +79,6 @@ magnum.cert_manager.backend =
     barbican = magnum.common.cert_manager.barbican_cert_manager
     local = magnum.common.cert_manager.local_cert_manager
     x509keypair = magnum.common.cert_manager.x509keypair_cert_manager
-
-[wheel]
-universal = 1
-
 [extras]
 osprofiler =
   osprofiler>=1.4.0 # 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>=2.0.0'],
     pbr=True)

test-requirements.txt

@@ -17,8 +17,7 @@ osprofiler>=1.4.0 # Apache-2.0
 os-testr>=1.0.0 # Apache-2.0
 python-subunit>=1.0.0 # Apache-2.0/BSD
 pytz>=2013.6 # MIT
-sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
+sphinx>=1.8.0,!=2.1.0 # BSD
 testrepository>=0.0.18 # Apache-2.0/BSD
 stestr>=2.0.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD