Added userIDView to wrap restify endpoint handlers and pre-fetch user ID from the extracted email in the _user field
Adopted userIDView for views that always need to fetch the user ID
Added userDataView for fetching all user data, and adopted it where possible; refactored generation of user views to stay DRY
Added documentation for wrapper views, and moved the result argument of each wrapper view to the front of the args list, using view.apply with the args list provided by redisView instead of hardcoding the args. This way arguments are never clobbered, and callers are free to ignore arguments at the end of the list.