Remove `<span class="nocase">` tags from final output.
Remove `<span class="nocase">` tags from final output.

This is an inefficient way to do it.  It would be better to
do this earlier in the citeproc processing, but I wasn't able
to figure out how to do this.

adunning/pandoc-citeproc,jkr/pandoc-citeproc,jgm/pandoc-citeproc