Security fix: no more matricola moving

We used to pass also 'matricola' every time we edit info. 
Now 'matricola' is the login name and can't be modified via API.
When a user send a request for changing his data, we identify him with login status. If he can modify, we read all previous data, where is present 'matricola' and start the dance between functions. But we don't want to make 'matricola' editable, so I remove it from the object with all (editable) data.