tox.ini: clean the pep8 target

There were some leftovers from the tox.ini from Ceilometer, which was used in
the beginning.

Change-Id: I16cef6dd65e449b029590f7da36c4462860dada8

tox.ini

@@ -3,17 +3,6 @@ minversion = 1.6
 skipsdist = True
 envlist = pep8
 
-#[testenv]
-deps = -r{toxinidir}/requirements.txt
-       -r{toxinidir}/test-requirements.txt
-install_command = pip install -U {opts} {packages}
-usedevelop = True
-setenv = VIRTUAL_ENV={envdir}
-         LANG=en_US.UTF-8
-         LANGUAGE=en_US:en
-         LC_ALL=C
-         EVENTLET_NO_GREENDNS=yes
-
 [testenv:pep8]
 # Install bounded pep8/pyflakes first, then let flake8 install
 deps = pep8==1.4.5
@@ -25,7 +14,5 @@ commands =
 
 
 [flake8]
-#ignore = H301,H306,H506
-builtins = _
-exclude=.venv,.git,.tox,dist,doc,./ceilometer/openstack/common,*lib/python*,*egg,tools,nova_tests,build
+exclude=.venv,.git,.tox,*egg,build
 show-source = True