Bs7 citations (#305)

* Initial attempt to build citation modal dialog box.

Citation link, generates modal dialog box whose content is the
results of a call to Zotero to get the citation.  Currently
using apa citation, there are many other options...

* Update Citation modal to include both rendered text and html

Allow the user to copy either the formatted 'pretty' text or
the raw html that creates the entry.

* Fix reference to prettier js files in script.

* Convert 'View on Zotero' and 'Citation' into buttons.

Move citations button to bottom of page with Zotero button.

* Move Zotero group id from hardcoded to a site parameter

* Fix button styles and clean up Hugo operation syntax.

In the process I discovered a couple minor errors in the
layout of the bibliography and fixed them.

Author: stumbo

config/_default/params.yaml

@@ -57,6 +57,9 @@ github_project_repo: https://github.com/interlisp/medley
 #  gcs_engine_id:  search engine 
 gcs_engine_id: 33ef4cbe0703b4f3a
 
+# Zotero Group ID for bibliography management
+zotero_group_id:  2914042
+
 # Footer Links
 # 
 # user:  End user relevant links. These will show up on