Enable hacking checks

Change-Id: I1bb5c28e9f726cf10e8562b738e7708785987461

test-requirements.txt

@@ -0,0 +1 @@
+hacking>=0.8.0,<0.9

tox.ini

@@ -8,12 +8,20 @@ usedevelop = True
 install_command = pip install -U {opts} {packages}
 setenv =
     VIRTUAL_ENV={envdir}
+deps =
+    -r{toxinidir}/requirements.txt
+    -r{toxinidir}/test-requirements.txt
 
 [tox:jenkins]
 downloadcache = ~/cache/pip
 
 [testenv:pep8]
-#commands = flake8 {posargs}
+commands = flake8 {posargs}
 
 [testenv:venv]
 commands = {posargs}
+
+[flake8]
+show-source = true
+builtins = _
+exclude=.venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,tools