Remove data-offset-bottom
add about us, sponsors page
Add buttons to navbar
Merge branch 'master' into draft

Conflicts:
	about_us.md
Fix sponsors link
Remove sidebar on about / sponsors page
Add logos to repo
Use site variable instead of hard static path
Add sponsors to a data file and make sponsors.html more liquidy
Fix "active" classes for navbar buttons
Refactor layouts a little further

This way, link tags and script tags and whatnot are all in a single
file. If we need to update that stuff, we just have to update
base.html.
Remove unused snippets from _includes/
Merge branch 'draft'