There are two mongos commands in API Version 1 that forward their parameters to internal commands: "drop" forwards to "_configsvrDropCollection" and "dropDatabase" forwards to "_configsvrDropDatabase".
Users should be permitted to call the mongos commands with apiVersion: "1", apiStrict: true, but the internal commands aren't in Version 1 and they'll reject these parameters. So, strip the API version parameters when forwarding.
