Mongo Connector: Add "database.whitelist" and "database.blacklist" configuration options

Currently the mongo connector supports collection.whitelist and collection.black list to control what mongodb data flows through to kafka. I am building a microservices architected system that leverages many different mongo databases (currently all inside the same mongo replica set). It would be very handy for me to be able to configure the connector based on the database name instead of having to manage the collection.whitelist.

(The MySQL Connector already supports a database.whitelist)