Update docs build job for new documentation PTI jobs

openstack infra use a new way for building documents[1]

[1]:See http://lists.openstack.org/pipermail/openstack-dev/2017-December/125710.html for details

Change-Id: I2cb0ae3130e61991e017d66b7b2e2711f3c21bfd

setup.cfg

@@ -11,11 +11,6 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
 
-[build_sphinx]
-all_files = 1
-build-dir = doc/build
-source-dir = doc/source
-
 [pbr]
 warnerrors = True
 

tox.ini

@@ -14,7 +14,10 @@ commands = python setup.py testr --slowest --testr-args='{posargs}'
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+deps =
+    -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+    -r{toxinidir}/requirements.txt
+commands = sphinx-build -b html doc/source doc/build/html
 
 [testenv:doc8]
 deps = -r{toxinidir}/requirements.txt doc8