Drop python 2.7 support and testing

Ussuri Communtiy-wide goal:
https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html

Remove also universal-wheel, this is py3 only now.

Co-Authored-By: Andreas Jaeger <aj@suse.com>
Change-Id: Ibac9edb043fa082322ed2f2272cc0b1727ae9009

.zuul.yaml

@@ -2,7 +2,6 @@
     templates:
       - check-requirements
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - periodic-stable-jobs
       - publish-openstack-docs-pti

setup.cfg

@@ -10,7 +10,6 @@ classifiers =
     Environment :: OpenStack
     Programming Language :: Python
     License :: OSI Approved :: Apache Software License
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -23,9 +22,6 @@ classifiers =
 packages =
     mox3
 
-[wheel]
-universal = 1
-
 [global]
 setup-hooks =
     pbr.hooks.setup_hook

test-requirements.txt

@@ -11,7 +11,6 @@ testtools>=2.2.0 # MIT
 six>=1.10.0 # MIT
 
 # this is required for the docs build jobs
-sphinx!=1.6.6,!=1.6.7,>=1.6.5,<2.0.0;python_version=='2.7'  # BSD
-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
 openstackdocstheme>=1.18.1 # Apache-2.0
 

tox.ini

@@ -1,8 +1,10 @@
 [tox]
-minversion = 2.0
-envlist = py27,py37,pep8
+minversion = 3.1.1
+envlist = py37,pep8
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 install_command = pip install {opts} {packages}
 deps =
        -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
@@ -11,17 +13,14 @@ deps =
 commands = stestr run --slowest {posargs}
 
 [testenv:docs]
-basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:pep8]
-basepython = python3
 deps =
     flake8<2.7.0,>=2.6.0
 commands = flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [flake8]
@@ -30,7 +29,6 @@ ignore = E721
 exclude=.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt