Install middleman-s3_sync (remove github-pages gem)
Specify 'vimcasts.org' bucket for S3 sync
Create a catch-all error page
Configure 301 redirects for feeds to force .rss/.xml extension
Configure 301 redirects for /classes/* -> /training/*
Configure 301 redirects for /blog/* -> /announcements/*

Only for those articles that were originally published on the blog but
have now been moved to the announcements section.
Remove meta-redirects for /classes/*
Update rake tasks to work without middleman-gh-pages
Exclude .DS_Store files from build

This ensures that .DS_Store files don't get synced to S3