Support for property modification versioning in transactional graph.

Support for handling properties modifications in versioned transactional
graph.
Bug fix for running non transactional long type graph tests.
Fire onVertexAdded event with a VersionedVertex.

Replaced the vertex instance within the onVertexAdded event
to contain a VersionedVertex instance instead of the base type.

This is required by event listeners to work with the VersionedVertex
instance. (for example, to set the VersionedVertex.forVersion property
to the latest graph version after the vertex was added.)
Bug fix with setting the private hash condition.

Vertex private hash should be set if old hash is null/empty OR
current hash equals the new specified hash. not AND when both
of these conditions match.
Bug fix to clear all content of TransactionData when clear() is invoked.