Connection converted to replica set
Fix some bugs in replica set connections

* Logic for using "MONGO_IS_REPLICA_SET" option was reversed
* "MongoReplicaSetClient" requires a "replicaSet" parameter, specifying
  the name of the replica set to connect to
Merge branch 'dev/dj-replica-connect'

* dev/dj-replica-connect:
  Fix some bugs in replica set connections
  Connection converted to replica set