[test] Rename BaseQuerierTC._access to BaseQuerierTC.admin_access
so it's consistent with CubicWebTC and avoid access to a protected attribute
which has been exposed by the removal of the 'session' property a few csets
earlier.
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