Backend - Schema definition hardcoded in entity classes

[JDTheRipperPC]

• Remove the schema definition harcoded in entity classes by a orm.xml file

References:
http://www.oracle.com/webfolder/technetwork/jsc/xml/ns/persistence/index.html
https://stackoverflow.com/questions/2737420/how-to-set-up-default-schema-name-in-jpa-configuration

[JDTheRipperPC]

This issue is not important in the development of the backend side, it could be resolved later.

I add some resources about persistent.xml & orm.xml:
https://dzone.com/articles/persisting-entity-classes