Cleanup py27 support

Make a few cleanups:
- Remove obsolete sections from setup.cfg
- Update requirements, no need for python_version anymore
- Switch to sphinx-build

Change-Id: Iaee99ab7ebbb7d866ef50b901e160be77538e566

requirements.txt

@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 
 pbr>=2.0.0,!=2.1.0 # Apache-2.0
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
+sphinx>=1.8.0,!=2.1.0 # BSD
 testtools>=1.4.0
 yasfb>=0.8.0
 openstackdocstheme>=1.19.0 # Apache-2.0

setup.cfg

@@ -10,15 +10,3 @@ classifier =
     Intended Audience :: Developers
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
-
-[build_sphinx]
-all_files = 1
-build-dir = doc/build
-source-dir = doc/source
-warning-is-error = 1
-
-[pbr]
-warnerrors = False
-
-[wheel]
-universal = 1

tox.ini

@@ -8,7 +8,6 @@ ignore_basepython_conflict = True
 basepython=python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
-install_command = pip install {opts} {packages}
 deps = -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/test-requirements.txt
 whitelist_externals = find
@@ -26,7 +25,7 @@ deps =
 setenv = PYTHONHASHSEED=0
 commands =
   find . -type f -name "*.pyc" -delete
-  python setup.py build_sphinx
+  sphinx-build -W --keep-going -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
 envdir = {toxworkdir}/docs