The JPA RepositorySource should provide way to specify the 'hibernate.hbm2ddl.auto' property

The 'hibernate.hbm2ddl.auto' property defines Hibernate's behavior for interacting/changing the database schema. Typically in production the database schema should already exist and should not be changed, while for development users may want to have Hibernate dynamically create the schema. Therefore, one value is not sufficient, and the JpaSource class should allow setting this value.

(It may be worthwhile to add the ability to set arbitrary properties on the JpaSource, and then modify the DnaConfiguration and DnaEngine code to look for JavaBean methods for the properties, and if there are none to look for and use a "setProperty(String,String)" method on the RepositorySource. This would make it possible to always add any Hibernate property to the JpaSource configuration.)