Establish proper idAttribute on EntryModels.

(I think that the way the types are being combined with the entry model
is wiping some significant backbone boilerplate, like this attribute.)

Also, some purely cosmetic changes to backbone.crypton.js (long lines,
etc) and EntriesCollection.js (adding "which" attribute to reduce
debugging guesswork).
Use ref to rootContainerID, rather than literal "entries".

In LoginView.js, SignupView.js.