improve organization of citation fields

[solomonr]

now, when someone adds a citation to a record, it simply includes all citation fields from our list.

use some javascript to organize this into several different groups. book, article, etc. so a user can select one of these predefined types, which will select a relevant subset of the total possible fields.

later, or possibly now, it would be good to manage these predefined types in the admin somehow. ie, so an admin user can create a new type of citation with the related set of fields. the js would then reference that.