Added a message field to Sesson Exception. Also, added a Project field to Session denoting which project the user has logged into. Created a method in SessionManager that handes project switching - removes the existing session and creates a new one for the user given the project to select. Added unit tests for this new function too. ManagerLayer now has direct access to the Project manager since it represents a Core feature that needs to be coordinating across Entities.
Forgot to add the updated cookie (with the project selected) in the PUT method... probably important.