Sync Gateway Contextual Logging for Databases

In sync gateway with multiple databases (pointing to  separate CBS buckets), the log messages from all databases are interleaved. This makes debugging and troubleshooting challenging  for the customer who are first level responders to issues reported by their clients as well as our own support teams. 

This is important in the context of multi-tenant deployments which will likely grow with the introduction of collections

Today, Sync Gateway supports contextual logging at user/request level, and not database specific

The enhancement is to identify log messages by database.