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

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

vitrage-dashboard 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: I21499eedca87193f78bcf633c21380d757c788f6

.zuul.yaml

@@ -25,8 +25,7 @@
     templates:
       - horizon-nodejs10-jobs-nonvoting
       - horizon-non-primary-django-jobs
-      - openstack-python-jobs-horizon
+      - openstack-python3-ussuri-jobs-horizon
-      - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
       - check-requirements
       - release-notes-jobs-python3

releasenotes/notes/drop-py-2-7-53892de5b1c6cf5b.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of vitrage-dashboard
+    to support py2.7 is OpenStack Train. The minimum version of Python now
+    supported by vitrage-dashboard is Python 3.6.

setup.cfg

@@ -13,8 +13,6 @@ 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 :: 3.6
     Programming Language :: Python :: 3.7

tox.ini

@@ -4,6 +4,7 @@ envlist = py37,py36,py3-{dj111,dj22},pep8,npm
 skipsdist = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -U {opts} {packages}
 setenv =
@@ -31,7 +32,6 @@ commands = {envpython} {toxinidir}/manage.py test vitrage_dashboard --tag integr
 
 
 [testenv:pep8]
-basepython = python3
 whitelist_externals =
   bash
   find
@@ -40,7 +40,6 @@ commands =
   bash {toxinidir}/tools/find_executables.sh
 
 [testenv:npm]
-basepython = python3
 passenv =
   HOME
   DISPLAY
@@ -53,20 +52,16 @@ deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -W -b html -d doc/build/doctrees doc/source doc/build/html
 
 [testenv:pdf-docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 envdir = {toxworkdir}/docs
 whitelist_externals =
@@ -84,5 +79,4 @@ builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
 
 [testenv:releasenotes]
-basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html