New code has been added to Response.class.php this year in commit
b94ac9a. Update LICENSE and Response.class.php copyright header with
year 2016.

We can't do this for every file in the project repository unless they
are actually changed, due to the way our copyright legislation works. We
also can't remove the mention of 2015, because most of the code was
initially published in 2015 and so remains copyrighted since that year.

The line is reduntant and more confusing than helpful. It belongs to
README. The original Expat license text doesn't include this line.

cenci0 has a lot of improved code in static/classes/Response.class.php
and static/upload.php. This can be seen in commit 5b77a4eaab.