Use new transactional Cypher endpoint (even without transactions)

[aseemk]

Even without doing all the work to support custom transactions, might it be worth using the new /db/data/transaction/commit Cypher endpoint now instead of the old /db/data/cypher endpoint?

@jexp suggested so in aseemk/node-neo4j-template#16.

Anecdotally, at @fiftythree, we did a quick experiment with the change internally, and we found that it was a bit slower — even using the lean JSON format instead of the full REST API format (which this driver currently needs, as it's hypermedia-driven).

So not sure if it's totally worth it. Open question: what advantage(s) does it have?

For reference, another driver (cypher-stream) is also evaluating this: https://github.com/brian-gates/cypher-stream/issues/3

[aseemk]

Closing in favor of #142.