OGM-182 Support Neo4j as Datastore

https://hibernate.onjira.com/browse/OGM-182

This is a first prototype that supports the embedded version of Neo4j.

The dialect converts every Entity into a Node and every Association into an oriented relationship from one node to another.

The attributes of the entity become  properties of the node. The same is true for the associations .

Sequence values are generated keeping a lock on a node and updating the property on the node.

Cheers,
Davide