Update bootstrap to v2.2.2.

Keeping the custom changes in bootstrap.css needed for sphinx, and specifying our fonts and stuff in style.css so that everything is close to what it was. jquery-migrate.js isn't needed anymore so remove it. Also remove the unneeded affix from bootstrap.
move the bootstrap overrides in style.css
Use a customized bootstrap. See bootstrap-info.md.
Merge branch 'bootstrap-update'