Photos now automatically selected from the directory /images/people,
assuming that the image has the same file name as the profile page,
switching md for jpg.

Add anonymous icon for missing profile photos.

Add skeleton profiles for the JS team.

Fix person card heights, add padding between cards.

* People may be assigned to multiple research projects.
* Plugin for advanced filter expressions (see also
  https://github.com/jekyll/jekyll/pull/4478)

It may be useful to keep in /vol/rr/www so that future people joining
the group know where to look for edit access.

References #4

* Remove "About" heading
* Hide "Group Publications" heading if there are none
* Centre card on page when no main column content is available
* Remove duplication of title and names configuration
* Shunt role onto same line as title

References #4