Create classes: Manager, Project, Task, Notification, NotificationQueue
Revert "Create classes: Manager, Project, Task, Notification, NotificationQueue"

This reverts commit 3e19ac04691da1bdabf0901a7ddfe33a68602653.
Revert "Revert "Create classes: Manager, Project, Task, Notification, NotificationQueue""

This reverts commit 8ed7e3eb6b6a6ec2118d9f908e418b52451a5f59.