Add autopep8 to tox.ini

autopep8 is an automated code formatting tool for python,
it does not know everything, also not super fast,
but it is faster than I can manually reformat the code.

tools/format.sh will call the formatting,
the tox will check did you called it.

Also adding a tox -eautopep8 way to use it.

autopep8 formats the lines in one way,
where tempest used a another way it was changed.

Change-Id: I6d51b14a5a5b87761071d0927fca23ba1651aa41
diff --git a/tox.ini b/tox.ini
index 4068054..72f48a5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -197,11 +197,21 @@
 whitelist_externals = rm
 
 [testenv:pep8]
+deps =
+    -r test-requirements.txt
+    autopep8
 basepython = python3
 commands =
+    autopep8 --exit-code --max-line-length=79 --experimental --diff -r tempest setup.py
     flake8 {posargs}
     check-uuid
 
+[testenv:autopep8]
+deps = autopep8
+basepython = python3
+commands =
+    autopep8 --max-line-length=79  --experimental --in-place -r tempest setup.py
+
 [testenv:uuidgen]
 commands =
     check-uuid --fix