WIP authors: inital release

* Introduces models and fields for author records.

* Updates config file with new module name.

Signed-off-by: Mateusz Susik <mateusz.susik@cern.ch>

TO DO:
+ tests
+ discuss name -> previous_name field
+ discuss where should config variables go (there are more general than only for authors usage)
+ change config variables names

This is a new subfield suggested by Anette. It is intended to store names that were used in the past by the authors.

For example it can be a maiden's name.