#8 Use a single persistence.xml file

[Kees Schotanus]

Currently there are more than one persistence.xml files.
It would be better to have only one.
Even better would it be to use Derby or some other database by default, provided the database does not need any configuration.
Unit tests for example should create the database structure.
Not sure if this is possible but it would allow for automatic versioning.
Currently when automatically creating a new version, the persistence.xml file is not copied so the tests will fail.