Introduce a class to organize general theme setup
Add support for HTML5 image galleries

This will stop WordPress from outputting default styles targetted
at the gallery in the DOM. These styles required the use of important
to override.
Bring over default styles for galleries from WordPress core
Add support for HTML5 captions, remove previous caption code

WordPress core handles captions in figures if we tell it that we
support HTML5. We aren't using any custom styles at this time, so
we can clean it up until necessary.
Remove unused style for now-extinct liner class
Move code for registering default theme menus to theme-setup
Correct syntax for calling method
Merge pull request #88 from washingtonstateuniversity/html5-support

[PR] Add HTML5 support for galleries and captions to parent theme