Make docs build again

Docs build was broken with:

TypeError: __init__() got an unexpected keyword argument 'handle_io_errors'

Upgrade sphinx requirements to those of a recent decade, and replace
the oslosphinx extension and requirement with openstackdocstheme.

At the same time, split the deps for the docs build out of
test-requirements.txt and put them in docs/requiremenst.txt as the gods
intended.

Change-Id: I6f82b5c37217ca2bdcf85c1ce07293b3d1026370
(cherry picked from commit 0d5042b0ce)

doc/requirements.txt

@@ -0,0 +1,4 @@
+Pygments
+docutils
+sphinx>=1.8.0,!=2.1.0  # BSD
+openstackdocstheme>=1.30.0  # Apache-2.0

doc/source/conf.py

@@ -36,7 +36,7 @@ def setup(app):
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
-extensions = [ 'oslosphinx' ]
+extensions = ['openstackdocstheme']
 
 todo_include_todos = True
 

test-requirements.txt

@@ -1,6 +1,2 @@
 pbr>=0.6,!=0.7,<1.0
-Pygments
-docutils
-sphinx>=1.1.2,<1.2
-oslosphinx
 bashate >= 0.2

tox.ini

@@ -20,9 +20,11 @@ commands =
 [testenv:docs]
 basepython = python3
 whitelist_externals = bash
+deps = -r{toxinidir}/doc/requirements.txt
 setenv =
   TOP_DIR={toxinidir}
   INSTALL_SHOCCO=true
 commands =
+    # TODO(efried): Use sphinx-build
     python setup.py build_sphinx
     bash tools/build_docs.sh