Flint 1.0.0 Release Candidate 2 (Major Design Changes)

Bugs
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- [x] Fix `wp_nav_menu` to satisfy strict class requirements
- [x] Fix font override for headings, so the font is still Open Sans
- [x] Fix `.navbar-brand` overflow for really long titles
- [x] Drop obsolete `<hgroup>`

Misc
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- [x] Update credit links; only one allowed according to WordPress guidelines
 - Switch link from Star Verte LLC to Flint
- [x] Remove schema options page
 - Wasn't implemented yet
 - Peer review says this is plugin territory, so it will go in Steel instead
- [x] Add `container` class to footer
- [x] Remove `featured_image_vertical`
- [x] Add filter to remove default gallery styles
- [x] Remove glyphicons (not needed)
- [x] Remove Font Awesome files (not needed)