core: Pass registry to storage and notification

What if the storage component wants to send notifications? What if (less
likely) the notification component wants to cancel the creation of an
annotation in response to the user clicking on a notification?

It seems more consistent to pass the registry to all of these functions.
Rename Notification/setNotification to Notifier/setNotifier
Rename Core.AnnotatorCore -> Core.Annotator

Appropriately namespaced, there's no reason to include the name of the
module in the function name.
core: Add setAuthorizer to core

Add the ability to set an authorizer implementation on the core. This is
preparatory work for moving the bulk of the Permissions plugin into the
UI, while the core authorization code becomes an implementation of the
Authorizer API.
authorizer: Add an authorizer component

This extracts the core piece of the (former) Permissions plugin into an
implementation of an Authorizer.
Remove traces of coffeescript from build tools
Temporarily comment out defunct Auth plugin specs
identifier: Add an identifier component

The identifier component is responsible for providing the identity of
the current user.
annotator: set default Identifier and Authorizer

This wires up the default Identifier and Authorizer, meaning that edit
and delete buttons will only be shown if they should be according to the
data in the annotation objects and the current user (which, by default,
is null).