[ussuri][goal] Drop python 2.7 support and testing

OpenStack is dropping the py2.7 support in ussuri cycle.

keystone-tempest-plugin is ready with python 3 and ok to drop the
python 2.7 support.

Complete discussion & schedule can be found in
- http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

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

Change-Id: I4c46dfbfb9e679d64f6cc6b99d8f63775ec3914a

.zuul.yaml

@@ -4,7 +4,6 @@
       - tempest-plugin-jobs
     check:
       jobs:
-        - keystone-dsvm-functional
         - keystone-dsvm-py3-functional
         - keystone-dsvm-functional-federation-opensuse15:
             voting: false
@@ -12,5 +11,4 @@
             voting: false
     gate:
       jobs:
-        - keystone-dsvm-functional
         - keystone-dsvm-py3-functional

setup.cfg

@@ -13,10 +13,10 @@ 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 :: 3
     Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
 
 [files]
 packages =

test-requirements.txt

@@ -4,8 +4,7 @@
 
 hacking>=1.1.0,<1.2.0 # Apache-2.0
 
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2  # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0
 
 # releasenotes

tox.ini

@@ -1,7 +1,8 @@
 [tox]
-minversion = 2.0
-envlist = py35,py27,pypy,pep8
+minversion = 3.1.1
+envlist = py35,py36,pypy,pep8
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
 usedevelop = True
@@ -11,30 +12,25 @@ setenv =
    PYTHONWARNINGS=default::DeprecationWarning
 deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'
+basepython = python3
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
-basepython = python3
 commands = sphinx-build -W -b html -d doc/buld/doctrees doc/source doc/build/html
 
 [testenv:releasenotes]
-basepython = python3
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]