Add a code smell test to make sure we're not using the raw system six

(So we know we have a recent enough version)

test/code-smell/use-compat-six.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# Do we want to check dynamic inventory, bin, etc?
+BASEDIR=${1-"lib"}
+
+SIX_USERS=$(find "$BASEDIR" -name '*.py' -exec grep -H six \{\} \;|grep import |grep -v ansible.compat)
+if test -n "$SIX_USERS" ; then
+  printf "$SIX_USERS"
+  exit 1
+else
+  exit 0
+fi