docs: Resolve issues with Sphinx 2.0

switch to openstackdocstheme which, unlike
the EOL'd oslosphinx theme, supports Sphinx 2.0.

Change-Id: I27e8612872830d55e0aed309f23194656fcc9369
ref: https://docs.openstack.org/openstackdocstheme/latest/

doc/source/conf.py

@@ -23,10 +23,16 @@ sys.path.insert(0, os.path.abspath('../..'))
 extensions = [
     'sphinx.ext.autodoc',
     #'sphinx.ext.intersphinx',
-    'oslosphinx',
+    'openstackdocstheme',
     'yasfb',
 ]
 
+
+# openstackdocstheme options
+repository_name = 'openstack/trove-specs'
+bug_project = 'trove-specs'
+bug_tag = 'doc'
+
 # Optionally allow the use of sphinxcontrib.spelling to verify the
 # spelling of the documents.
 try:
@@ -70,6 +76,7 @@ pygments_style = 'sphinx'
 # html_theme_path = ["."]
 # html_theme = '_theme'
 # html_static_path = ['static']
+html_theme = 'openstackdocs'
 
 # Output file base name for HTML help builder.
 htmlhelp_basename = '%sdoc' % project

requirements.txt

@@ -1,6 +1,6 @@
-pbr>=0.6,<1.0
-oslosphinx
-sphinx>=1.1.2,<1.2
+openstackdocstheme>=1.11.0
+sphinx!=1.6.6,!=1.6.7,<2.0.0;python_version=='2.7'  # BSD
+sphinx!=1.6.6,!=1.6.7;python_version>='3.4'  # BSD
 testrepository>=0.0.18
 testtools>=0.9.34
 yasfb>=0.5.1