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
  * Some other sections are obsolete
- Update classifiers
- Update requirements, no need for python_version anymore

Change-Id: I57dc2210d369cb89ad2de7d2c304a8f225fd6adf

requirements.txt

@@ -2,8 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-dnspython>=1.14.0;python_version=='2.7' # http://www.dnspython.org/LICENSE
+dnspython3!=1.13.0,!=1.14.0,>=1.12.0 # http://www.dnspython.org/LICENSE
-dnspython3!=1.13.0,!=1.14.0,>=1.12.0;python_version>='3.0' # http://www.dnspython.org/LICENSE
 ddt>=1.0.1 # MIT
 testtools>=2.2.0 # MIT
 tempest>=17.1.0 # Apache-2.0

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/designate-tempest-plugin/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Environment :: No Input/Output (Daemon)
@@ -14,15 +15,13 @@ 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
     Topic :: Internet :: Name Service (DNS)
 
-[global]
-setup-hooks =
-    pbr.hooks.setup_hook
-
 [files]
 packages =
     designate_tempest_plugin
@@ -31,15 +30,7 @@ packages =
 tempest.test_plugins =
     designate = designate_tempest_plugin.plugin:DesignateTempestPlugin
 
-[build_sphinx]
-all_files = 1
-build-dir = doc/build
-source-dir = doc/source
-
 [egg_info]
 tag_build =
 tag_date = 0
 tag_svn_revision = 0
-
-[wheel]
-universal = 1

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)