Add contributors to object entries

[geealbers]

This should come after the object.yml file and object Markdown files have been created (issue #1). And I can add detail to this when the work commences but the basic plan is to:

• [x] add contributor data to the publication.yml file
• [x] reference contributors in the object Markdown files by id
• [x] add shortcodes to display the contributor initials in the proper place in the entry text. Probably like {{< q-contributor range="page" type="initials" align="right" >}}

Though I'm already seeing an issue in that we need to be able to display curatorial initials on one part of the page, and conservator initials on another. So we may need to rethink the last item there. May involve not using the shortcode at all, or modifying the shortcode to work the way we need it to.

[geealbers]

From the transmittal memo:

Issue of placement of author initials in entries (Greg to handle); need to distinguish between curatorial authors, whose initials would normally be placed after the bibliography, and the conservation authors, whose initials would go after the technical description.

[geealbers]

Done with 61891f3