testing: added small unit test example
added test case for successful signup
implemented signup backend
implemented registration frontend
show user name welcome message after registration
implemented login backend
implemented login frontend
implemented logout
implemented main controller with test cases
corrected typing error in signup view
refactored index.jsp
added example code for simple web login

The application provides a simple way to signup and login using a cookie
to save the session id. There is currently no database in use, instead
dummy objects immitate the persistency layer. The example code is
is not utilizing any advanced Spring features, so it should be straight
forward to understand was is happening here.