Add fixes for building the doc package

- always reference the swift module from the package we're building
- use oslo.sphinx from python-oslo-sphinx 1.x
Based on Nova/Glance EPEL patch by Pádraig Brady <P@draigBrady.com>
Stop using intersphinx

Remove intersphinx from the docs build as it triggers network calls that
occasionally fail, and we don't really use intersphinx (links other
sphinx documents out on the internet)

This also removes the requirement for internet access during docs build.

This can cause docs jobs to fail if the project errors out on
warnings.

Change-Id: I71e941e2a639641a662a163c682eb86d51de42fb
Related-Bug: #1368910