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
- Use sphinx-build everywhere
- Update classifiers
- Update requirements, no need for python_version anymore

Change-Id: I23a3b98e41099b74a4da95cc5c6e2d3171c0809c

setup.cfg

@@ -5,6 +5,7 @@ description-file = README.rst
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/python-monascaclient/latest/
+python-requires = >=3.6
 classifier =
     Environment :: Console
     Intended Audience :: Information Technology
@@ -12,8 +13,8 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -24,22 +25,3 @@ packages = monascaclient
 [entry_points]
 console_scripts =
     monasca = monascaclient.shell:main
-
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-warning-is-error = 1
-
-[build_releasenotes]
-all_files = 1
-build-dir = releasenotes/build
-source-dir = releasenotes/source
-
-[wheel]
-universal = 1
-
-[egg_info]
-tag_build =
-tag_date = 0
-tag_svn_revision = 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

@@ -13,6 +13,6 @@ testtools>=2.2.0 # MIT
 
 # documentation
 doc8>=0.6.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.5;python_version>='3.4' # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.5 # BSD
 reno>=2.5.0 # Apache-2.0
 openstackdocstheme>=1.18.1 # Apache-2.0

tox.ini

@@ -67,13 +67,13 @@ commands =
 description = Builds developer documentation
 commands =
   rm -rf {toxinidir}/doc/build {toxinidir}/doc/source/contributor/api
-  python setup.py build_sphinx
+  sphinx-build -a -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
 description = Called from CI script to test and publish the Release Notes
 commands =
   rm -rf releasenotes/build
-  sphinx-build -a -E -d {toxinidir}/releasenotes/build/doctrees -b html \
+  sphinx-build -a -W -E -d {toxinidir}/releasenotes/build/doctrees -b html \
     {toxinidir}/releasenotes/source {toxinidir}/releasenotes/build/html
 
 [testenv:checkniceness]