adding introduction to citing author and citing work

[acholyn]

closes #383

[tcouch]

When adding or updating an introduction on a citing_work or citing_author, if it includes a mention of a bibliography item, you get the following error:

File "/app/rard/utils/basemodel.py", line 319, in link_bibliography_mentions
     for ant in antiquarians:
UnboundLocalError: local variable 'antiquarians' referenced before assignment

We can't really assign an antiquarian to a citing author or citing work, but we would like to link bibliography items in the same way. We'll have to expand the link_bibliography_mentions method to handle this.

[acholyn]

I've also just noticed that we don't have a shortcode for citing authors in mentions, so how do we mention them? Or is this just another thing to do for this PR

[tcouch]

I've also just noticed that we don't have a shortcode for citing authors in mentions, so how do we mention them? Or is this just another thing to do for this PR

I guess the researchers have just never needed to mention citing authors. Is there a reason we would want to add it?

[acholyn]

Is there a reason we would want to add it?

Perhaps not, I suppose the researchers can always request this in future

[acholyn]

Possible qol: when clicking the refresh, it should do a loader since typically on a CA it will already be updated and won't actually change