Docs are generated incorrectly

When docs are generated with pbr command 'warnerrors = True'
there are many doc problems that are shown. This patch fixes
these problems.

Change-Id: Idb804ab924782b6d7d379494987bdba2acbce568
Closes-Bug: #1557235

tox.ini

@@ -21,6 +21,9 @@ commands = flake8
 [testenv:venv]
 commands = {posargs}
 
+[pbr]
+warnerror = True
+
 [testenv:functional]
 # See glanceclient/tests/functional/README.rst
 # for information on running the functional tests.
@@ -39,10 +42,11 @@ commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasen
 
 [flake8]
 # H233  Python 3.x incompatible use of print operator
+# H301  one import per line
 # H303  no wildcard import
 # H404  multi line docstring should start with a summary
 
-ignore = F403,F812,F821,H233,H303,H404
+ignore = F403,F812,F821,H233,H301,H303,H404
 show-source = True
 exclude = .venv*,.tox,dist,*egg,build,.git,doc,*openstack/common*,*lib/python*,.update-venv