Show / hide toggle for more snippets

Using some ideas from Emily Bamsey's branch, but avoiding jQuery and
keeping the changes extremely specific to show/hide snippets, with a
focus on relying on simple class changes and a mobile-first design.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Just use + / - to show hide snippets

Enclosed in a simple border to anchor the show/hide behaviour to the
correct snippet.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Display linkable year facets, toggling the URL

Make the linkable year facets add the year to the URL and resubmit the
request, or alternately remove the year from the URL. Next: to teach the
search backend to limit by year.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Enable year facet to affect search results

Not the prettiest code, concatenating strings for the SQL query, but
workable for now. Also add a little more semantic HTML to allow for more
stylish CSS down the road.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Don't show/hide snippets for single snippet results

We were blithely showing the +/- when there was nothing more to show or
hide; don't do that :)

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Support paging, simplify URL creation

Define a jinja2 macro to handle creating URLs, rather than handcrafting
the URLs ourselves in each situation. Also, add support for paging
through results (requiring a minor change to the restapp parameters as
well).

Signed-off-by: Dan Scott <dscott@laurentian.ca>