Proof of concept for auth ActionBuilder

This allows Identity to easily create actions that require a logged-in
user.

If the user is logged in, the details extracted from the cookie are
included on a User object added to the request parameter as
request.user.

If the user is not logged in, we issue a redirect to the dentity
signin page.
TODO: The signin page's return URL won't be right at the moment.
facebook autosignin
AuthAction with working signin redirect
Simplify Auth implementations and add ScGuU provider
Include Auth on custom request for AuthAction
Add 'join' api helper to perform calls simultaneously
Working first draft of email prefs page
AuthRequest is now WrappedRequest instance

This negates the need for the implicit conversion.
Another step towards email prefs
MasterClasses. Doesn't really work but I need a savepoint.
Working MasterClasses endpoint
Just use Joda DateTime.
Add Masterclass to dev-build
Fix typo
Update masterclasses markup
User preference form

Depends on the user-prefs and forward-identity-cookie Identity
branches for a compatibleID API.

This introduces a working-ish email prefs form. Still needs CSRF
protection and tests.
check whether browsing device is desktop or mobile before attempting facebook autosign flow
initial merge of master
correctly merge app.js
Merged in master