Enable H302 rule everywhere

This patch enables the use of the H302 hacking rule everywhere. With
one exception of the client class imports in clients.py, this
is intentionally ignored.

Change-Id: Ia0ef5e44a411ccd6e6c12f9cf64427a96e021b47
diff --git a/tox.ini b/tox.ini
index ef49b28..2110362 100644
--- a/tox.ini
+++ b/tox.ini
@@ -99,6 +99,6 @@
 
 [flake8]
 # E125 is a won't fix until https://github.com/jcrocholl/pep8/issues/126 is resolved.  For further detail see https://review.openstack.org/#/c/36788/
-ignore = E125,H302,H404
+ignore = E125,H404
 show-source = True
 exclude = .git,.venv,.tox,dist,doc,openstack,*egg