Use pep8 replace py27

Depends-on: I98d4c3e9924346b826e5267b0b7c6b73f86741aa
Change-Id: Iada900ac58f0cbfd5035a9cc371669dc998e8d80

.zuul.yaml

@@ -3,7 +3,7 @@
       - openstack-specs-jobs
     check:
       jobs:
-        - openstack-tox-py27
+        - openstack-tox-pep8
     gate:
       jobs:
-        - openstack-tox-py27
+        - openstack-tox-pep8

tox.ini

@@ -1,8 +1,6 @@
 [tox]
-# Hold back to 1.4, since that's what's in Fedora 20 repos
-# and we don't need anything newer for watcher-specs tests
-minversion = 1.4
-envlist = docs,py27,pep8
+minversion = 2.0
+envlist = docs,pep8
 skipsdist = True
 
 [testenv]
@@ -29,10 +27,13 @@ commands =
 
 [testenv:pep8]
 basepython = python3
-deps = -r{toxinidir}/test-requirements.txt
+deps =
+  -r{toxinidir}/requirements.txt
+  -r{toxinidir}/test-requirements.txt
 commands =
-    doc8 doc/source/ README.rst
-    flake8 {posargs}
+  find . -type f -name "*.pyc" -delete
+  stestr run --slowest {posargs}
+  flake8 {posargs}
 
 [flake8]
 ignore = E128