Switch to newer openstackdocstheme and reno versions

Switch to openstackdocstheme 2.2.0 and reno 3.1.0 versions. Using
these versions will allow especially:
* Linking from HTML to PDF document
* Allow parallel building of documents
* Fix some rendering problems

Update Sphinx version as well.

Set openstackdocs_pdf_link to link to PDF file. Note that
the link to the published document only works on docs.openstack.org
where the PDF file is placed in the top-level html directory. The
site-preview places the PDF in a pdf directory.

openstackdocstheme renames some variables, so follow the renames
before the next release removes them. A couple of variables are also
not needed anymore, remove them.

Change-Id: I3f3d44ec367e40c14d5ec589a22df395346970b4

doc/requirements.txt

@@ -1,7 +1,7 @@
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2 # BSD
+sphinx>=2.0.0,!=2.1.0 # BSD
 sphinxcontrib-httpdomain>=1.3.0 # BSD
 sphinxcontrib-blockdiag>=1.5.4 # BSD
 sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD
-reno>=2.5.0 # Apache-2.0
+reno>=3.1.0 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
-openstackdocstheme>=1.20.0 # Apache-2.0
+openstackdocstheme>=2.2.0 # Apache-2.0

doc/source/conf.py

@@ -59,8 +59,9 @@ pygments_style = 'sphinx'
 html_theme = 'openstackdocs'
 
 # openstackdocstheme options
-repository_name = 'openstack/bifrost'
-use_storyboard = True
+openstackdocs_repo_name = 'openstack/bifrost'
+openstackdocs_pdf_link = True
+openstackdocs_use_storyboard = True
 
 # Output file base name for HTML help builder.
 htmlhelp_basename = 'bifrostdoc'

releasenotes/source/conf.py

@@ -38,7 +38,6 @@ source_suffix = '.rst'
 master_doc = 'index'
 
 # General information about the project.
-project = u'bifrost'
 copyright = u'2015, Ironic Developers'
 
 # If true, '()' will be appended to :func: etc. cross-reference text.
@@ -63,12 +62,9 @@ html_theme = 'openstackdocs'
 htmlhelp_basename = 'BifrostReleaseNotesdoc'
 
 # openstackdocstheme options
-repository_name = 'openstack/bifrost'
-bug_project = 'bifrost'
-bug_tag = ''
-
-# Must set this variable to include year, month, day, hours, and minutes.
-html_last_updated_fmt = '%Y-%m-%d %H:%M'
+openstackdocs_repo_name = 'openstack/bifrost'
+openstackdocs_bug_project = 'bifrost'
+openstackdocs_bug_tag = ''
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass