BookEntity has watchers & return book sends email to watchers (hopefully).
BookFacade - watchBook
BookRestService - watchBook
BookTo contains information about watching/not watching.
Unwatch method in rest/facade/entity.
Watch/Unwatched return BookTO instead of null.
Show watch/unwatch buttons & act on them; create email templates.
Change watch button style.
Remove controllers.js from script list.
TODOs for refactoring.
Reformat code in http-auth-interceptor.
Merge master into ExtendedBookDetails