When an addShard() command gets committed by the config server, the event should be registered in the oplog of other shards of the cluster to ensure that mongos processes will eventually be notified.

The purpose of this ticket is defining a new command to pass a descriptor of the committed addShard() operation to a remote shard.
The command request should include:

• The name of the added shard
• The connection string of the added shard
• A timestamp associated to the commit time of addShard