All database code to separate modules

[bertspaan]

API, IO, Core and Graphmalizer now all have some code to communicate with Redis, Elasticsearch and Neo4j, and they all initialize their own connections to those DBs using histograph-config.

• Move all DB code to separate modules:
  • histograph-db-elasticsearch
  • histograph-db-neo4j
  • histograph-db-redis
• Each DB module has its own API (e.g. to search), but some have shared functionality (e.g. to do bulk writes)
• Each module uses histograph-config to get username, port, password, etc.

[bertspaan]

See:

• https://github.com/nypl-spacetime/histograph-db-postgis
• https://github.com/nypl-spacetime/histograph-db-elasticsearch
• https://github.com/nypl-spacetime/histograph-db-graphmalizer

And see https://github.com/nypl-spacetime/histograph-core