access: customized access configuration

* Adds new inspire module overlay for Invenio access module.

* Sets up some default DEMO cataloger roles.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
And just an extra question, when we define an existing module from Invenio in the INSPIRE overlay and create our own ```config.py``` , that overrides completely the configuration from Invenio?? Or extends it?