[eclipselink-dev] Fix for Bug 350599 - Order of deletes change causes is

[Tom Ware <tom.ware@xxxxxxxxxx>]

https://bugs.eclipse.org/bugs/show_bug.cgi?id=350599

After much discussion, we decided that we would revert the default of deleting
1-Ms as a collection.  We will revert to deleting the entities individually
except in the case where the target of the relationship has either no
relationships of a single relationship that represts a backpointer to the
source.

@DeleteAll and <delete-all/> config is only available in trunk.

Reviewed by James Sutherland and Guy Pelletier

Tested with JPA LRG and Core LRG

Added testing to PrivateOwned model for core change in both streams

Added additional testing for Annotation and XML to PrivateOwned model and to
eclipselink-orm model in trunk stream