Drop back to Hibernate 5.0.x

[wilkinsona]

After much discussion, we've decided to go with Hibernate 5.0.x as the default version for 1.4, while also providing samples and documentation showing how to use 5.2.x.

[rakpan]

This is a very good decision in my opinion..

[zhanhb]

It seems hibernate 5.2.0 is a mistake. hibernate entitymanager 5.2.1 is availiable from maven central.