Add support for publications

[alancleary]

Specifically, add jekyll-scholar as a dependency of the theme and then create a layout for a Publications page that sites can use to list their project publications.

• Add an example of this page to the starter site
• Update a blog post in the starter site to show how this can be used to added citation to a blog post
• Use this to address LIS-Jekyll site needs 'Cite LIS' info in a prominent location. jekyll-legumeinfo#120 on legumeinfo
• Document all of these uses in README.md