Datagraph 445

@jexp - This PR replaces https://github.com/spring-projects/spring-data-neo4j/pull/171 with change to use subclass on Spring DataAccessException instead of propagating raw ConstraintViolationException up plus a fix to use correct project version in pom file.

Unfortunately the REST scenario does not provide us with enough info to work out that this
was a constraint violation (other than parsing the message itself which is not great) as it
merely throws an IllegalStateException when no content is found for a response when adding
labels. The code below is the offender and the REST API itself would need to change for
us to be able to deal with this appropriately in SDN

org.neo4j.rest.graphdb.ExecutingRestAPI

    . . .
    @Override
    public void addLabels(RestNode node, String...labels) {
        RequestResult response = getRestRequest().with(node.getUri()).post("labels", asList(labels));

        if (response.statusOtherThan(Status.NO_CONTENT)) {
            throw new IllegalStateException("error adding labels, received " + response);
        }
    }