ETL between databases with ndjson

[lbeckman314]

From the task catalog we should be able to:

• extract database contents into ndJSON format
• load ndJSON data into any of the databases

This will help with users migrating from BoltDB to the more performant MongoDB. This will allow for easier translations between database formats when using Funnel.

Example function calls:

# Outputs the data dump from BoltDB
funnel extract bolt --output data.ndjson

# Inputs the data dump into MongoDB
funnel load mongo --input data.ndjson