Changes

tsk8 Adds the action to remove a user
Adds an @MappedSupperClass to indicate the logical deletion of the 
objects of the entities that need it. Adds the role attribute for the
user entity with its get and set. Contructors initialize this variable
to "USER". Adds the delete action in the service layer. Adds test to
verify that the user is eliminated correctly. Adds an XML for user
tests.
Adds the role and the check of elimination of the user in the team XML
so that the test work correctly.