Share nodes & rels across db URLs

[aseemk]

We at @fiftythree use a clustered Neo4j setup, and for scalability/performance, we see ourselves wanting to split our queries between the master and the slaves depending on whether they need to be immediately consistent or can be eventually consistent.

To do that, we'd currently need two different GraphDatabase instances (pointing to different URLs), but there isn't currently a way to share Node or Relationship instances between the separate db instances. E.g. make a read query against a slave db, get back nodes/rels, and perform a write query from them to the master db.

We'll probably need to rethink the API to support this scenario...

[aseemk]

Another use case: cache sharding. E.g. sending user lookups to instance A or B depending on country.

[aseemk]

The currently ongoing v2 redesign will change this driver to no longer be hypermedia-driven (and generally be functional/stateless), so these should no longer be a problem.

Issue: #143 / PR: #145
WIP docs: https://github.com/thingdom/node-neo4j/blob/v2/API_v2.md

Closing this as "won't fix" accordingly.