Remove preview unpublished plugin

Jekyll now has drafts
Update date plugin for new jekyll

No idea if this is actually correct or not
Use new jekyll commands in Rakefile
Update gems

Jekyll goes to latest version, pygments.rb is replaced by rouge
Remove pagination plugin

Use jekyll builtin pagination instead
Merge branch 'update-jekyll' into julian-blog
Update posts for new jekyll version
Do pagination correctly with new jekyll
Put quotes around title to fix syntax highlighting
Update config for new jekyll