Treat doc warnings as errors

With the switch to build-sphinx, the setting to treat warnings
as errors was missed. This adds the -W flag to bring back this
setting.

Also cleaning out doc related settings from setup.cfg as they
are no longer being used.

Change-Id: Ic45deb8acdebc53f7cad98eb5c9fd9388929eee9

setup.cfg

@@ -26,15 +26,6 @@ packages =
 oslo.config.opts =
     oslo.versionedobjects = oslo_versionedobjects._options:list_opts
 
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-warning-is-error = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [compile_catalog]
 directory = oslo_versionedobjects/locale
 domain = oslo_versionedobjects

tox.ini

@@ -25,7 +25,7 @@ commands = {posargs}
 
 [testenv:docs]
 deps = -r{toxinidir}/doc/requirements.txt
-commands = sphinx-build -b html doc/source doc/build/html
+commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:cover]
 commands = python setup.py test --coverage --coverage-package-name=oslo_versionedobjects --testr-args='{posargs}'