MUMNOTPLT-31 Read that stuff

Adds the read/unread state in the notification response served up by the server.

Adds some controller methods to only fetch read vs unread notifications.  May or may not be useful now that state is served up with the notification response.
If its something else what do we do? just thinking of "archived" in the future.

Do we want to change the attribute to be state, and the value is the current state (read, unread, archived)? #thinkingWhileTyping