[qunit] remove unused 'data_files' parameter
Its use was removed when we stoppped pointing firefox at file://
web/test/jstests/ajax_url2.html has never actually been used, it's only
been ever mentioned in a QUnit comment.
Schema of the data
------------------
First take a look at the data schema_ then try to remember that you are browsing
through a heap of data by applying stylesheets to the results of queries. This
site is not a content management system with items placed in folders. It is an
interface to a database which applies a view to retreived data.
.. _schema: ../schema