add db.removeDb()

[maloguertin]

We have a multi tenant architecture where each tenant has it's own DB. At some point we had to manage the connections to the DBs to avoid memory leaks.

This is the clean up function we have:

const handleCleanUp = removedDb => {
    delete db.relatedDbs[removedDb.name]
    db.otherDbs = db.otherDbs.filter(otherDb => removedDb != otherDb)
}

It's not much of a problem but it would be interesting to be able to have an officialy supported way of doing this:

const mOtherDb = db.useDb('my-other-db')
db.removeDb('my-other-db')