Follow the new PTI for document build

For compliance with the Project Testing Interface, as described in:
https://governance.openstack.org/tc/reference/project-testing-interface.html

For more detailed information, please refer to:
http://lists.openstack.org/pipermail/openstack-dev/2017-December/125710.html

Change-Id: I02fee6362fe179e4ce1eafabd83aa054ff0459dc
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

doc/requirements.txt

@@ -0,0 +1,5 @@
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+openstackdocstheme>=1.18.1 # Apache-2.0
+
+# releasenotes
+reno>=2.5.0 # Apache-2.0

test-requirements.txt

@@ -6,12 +6,7 @@ hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 
 coverage!=4.4,>=4.0 # Apache-2.0
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
-openstackdocstheme>=1.18.1 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
-
-# releasenotes
-reno>=2.5.0 # Apache-2.0

tox.ini

@@ -4,6 +4,8 @@ envlist = py{27,34,35},pep8
 
 [testenv]
 install_command = pip install {opts} {packages}
+whitelist_externals =
+  rm
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/test-requirements.txt
@@ -19,10 +21,18 @@ commands = {posargs}
 commands = python setup.py test --coverage --testr-args='{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}/doc/requirements.txt
+commands =
+  rm -rf doc/build
+  sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
+deps =
+  {[testenv:docs]deps}
 commands =
+  rm -rf releasenotes/build
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:debug]