Updating Dialogs JAR

Replacing the old dialogs jar with a new one created for the new
version of JavaFX.
UserBean

Adding constructor for just username and password fields.
Main

Using interface and presenter to create login screen.
Calendar

Creation of calendar interface, listener, and presenter.
LoginScreen

Creation of login screen interface, listener, and presenter.
NewUserScreen

Creation of new user screen interface, listener, and presenter.
Refactoring and Repackaging

Repackaging GUI files and removing an unneeded dialog box class because
we found the Dialogs library.