Add pages from the Jekyll tutorial

Gemfile

Gemfile.lock

_authors/jill.md

_authors/ted.md

_config.yml

_data/navigation.yml

_includes/navigation.html

_layouts/author.html

_layouts/default.html

_layouts/post.html

_posts/2019-02-13-bananas.md

_posts/2019-02-13-kiwis.md

_sass/main.scss

about.md

assets/css/styles.scss

blog.html

index.html

staff.html