Added, as an exercise, a dummy login form. It doesn't do any actual
login; it's just a form I made for practicing form processing. Also made
the form data session scoped. Added a bunch of logging in
LoginController in order to investigate what data can be found in
global, session and request scopes as well as what request parameters
are and what data is to be found in the model. Added Maven dependency
javax.servlet:javax.servlet-api:3.0.1 in the "provided" scope, to be
able to reference the HttpServletRequest from the LoginController.