Bump the openstackdocstheme extension to 1.20

Some options are now automatically configured by the version 1.20:
- project
- html_last_updated_fmt
- latex_engine
- latex_elements
- version
- release.

Change-Id: Icd8404026ff5a73129a22b6c89b5cfd6c57432fb

doc/source/conf.py

@@ -46,7 +46,6 @@ master_doc = 'index'
 repository_name = 'openstack/python-novaclient'
 bug_project = 'python-novaclient'
 bug_tag = 'doc'
-project = 'python-novaclient'
 copyright = 'OpenStack Contributors'
 
 # List of directories, relative to source directory, that shouldn't be searched

releasenotes/source/conf.py

@@ -43,15 +43,8 @@ source_suffix = '.rst'
 master_doc = 'index'
 
 # General information about the project.
-project = u'Nova Client Release Notes'
 copyright = u'2015, Nova developers'
 
-# Release notes are version independent.
-# The short X.Y version.
-version = ''
-# The full version, including alpha/beta/rc tags.
-release = ''
-
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #language = None
@@ -178,17 +171,6 @@ htmlhelp_basename = 'NovaClientReleaseNotestdoc'
 
 # -- Options for LaTeX output ---------------------------------------------
 
-latex_elements = {
-# The paper size ('letterpaper' or 'a4paper').
-#'papersize': 'letterpaper',
-
-# The font size ('10pt', '11pt' or '12pt').
-#'pointsize': '10pt',
-
-# Additional stuff for the LaTeX preamble.
-#'preamble': '',
-}
-
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).