WIP authors: base record

* Defines fields and models for author base record.
* Adds new function for jsonalchemy models definitions.
* Includes tests for author base record.

There is one thing to add here: We need to store the list of the publications. This is a relaton between an author and a publication and this directly touches the subject of monday's meeting.
Probably a documentation with _HOW TO_ is needed. It is not obvious that this file should be inherited, and one can expand both `ids` and `names` definitions.