Bibtex page & random key generator

Added page that shows bibtex for every reference in database, and added a random key generator (now a random key will be generated for the bibtex if the user doesn't supply one).

Do note that the random key is different each time the page is loaded, and this is intended (we don't want to save the key in the database, in case the user wants to add a key later). Or do we? We can always change this behaviour later.

This change also affects the bibtex that shows on the page of a single reference.