Get ready for os-api-ref sphinx theme change

We need some magic to keep the build working as we move away from
oslosphinx and towards openstackdocstheme, the theme we are going to
use for all the docs.

For more details see:
http://lists.openstack.org/pipermail/openstack-dev/2016-August/101996.html

Change-Id: I378b1afade4725758c024e06b239b0af64d1b19a

api-ref/source/conf.py

@@ -29,6 +29,36 @@ import subprocess
 import sys
 import warnings
 
+# TODO(Graham Hayes): Remove the following block of code when os-api-ref is
+# using openstackdocstheme
+
+import os_api_ref
+
+if getattr(os_api_ref, 'THEME', 'olsosphinx') == 'openstackdocstheme':
+    # We are on the new version with openstackdocstheme support
+
+    extensions = [
+        'os_api_ref',
+    ]
+
+    import openstackdocstheme  # noqa
+
+    html_theme = 'openstackdocs'
+    html_theme_path = [openstackdocstheme.get_html_theme_path()]
+    html_theme_options = {
+        "sidebar_mode": "toc",
+    }
+
+else:
+    # We are on the old version without openstackdocstheme support
+
+    extensions = [
+        'os_api_ref',
+        'oslosphinx',
+    ]
+
+# End temporary block
+
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
@@ -41,11 +71,6 @@ sys.path.insert(0, os.path.abspath('./'))
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 
-extensions = [
-    'os_api_ref',
-    'oslosphinx',
-]
-
 # The suffix of source filenames.
 source_suffix = '.rst'