Fix ./run_tests.sh --pep8

Create a common script to call flake8 to share flake8 options and
make tox and run_tests.sh use this script.

Fixes bug: 1179331

Change-Id: I92dc54fa3f4bb22aa39bde226b6d769088f9a2e3

tools/run_pep8.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+set -e
+
+echo "Running flake8 ..."
+# E711/E712 comparison to False should be 'if cond is False:' or 'if not cond:'
+#        query = query.filter(Component.disabled == False)
+# E125 continuation line does not distinguish itself from next logical line
+# H301 one import per line
+# H302 import only modules
+# TODO(marun) H404 multi line docstring should start with a summary
+# TODO(marun) H901,902 use the not operator inline for clarity
+# TODO(markmcclain) H202 assertRaises Exception too broad
+PEP8_IGNORE="E711,E712,E125,H301,H302,H404,H901,H902,H202"
+PEP8_BUILTINS="_"
+PEP8_EXCLUDE=".venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,tools"
+flake8 --exclude=$PEP8_EXCLUDE --ignore=$PEP8_IGNORE --show-source --builtins=$PEP8_BUILTINS .