When connecting in replica set mode, passing the wrong replica set name to Client#initialize results in an empty cluster (naturally), but doesn't tell the user that they've connected to a cluster with zero active servers.

In such a scenario, it doesn't make sense to allow the user to continue, since nodes cannot join a replica set which do not share that replica set's name, so the topology will never change to include the non-existent replica set.

The result of any operation will be that "no servers are available", but the reason that they aren't available (no servers matched the replica set name, and the cluster is empty) is not immediately apparent to the user.

Instead, I propose that during topology discovery, if a replica set name is given and no nodes in the RS match the given replica set name, the driver should fast-fail with an exception.

 > m = Mongo::Client.new ["localhost:27019"], replica_set: "foobar", read: {mode: :secondary_preferred}
 => #<Mongo::Client:0x2380 cluster=localhost:27019, luna:27019>
> m["test"].find().first

Mongo::Error::NoServerAvailable: No server is available matching preference: #<Mongo::ServerSelector::SecondaryPreferred:0x38af1bf6 @tag_sets=[], @options={:database=>"admin", :replica_set=>"foobar", :read=>{:mode=>:secondary_preferred}}, @server_selection_timeout=30>
        from /usr/local/rvm/gems/jruby-head/gems/mongo-2.0.4/lib/mongo/server_selector/selectable.rb:99:in `select_server'
        from /usr/local/rvm/gems/jruby-head/gems/mongo-2.0.4/lib/mongo/collection/view/iterable.rb:38:in `each'
        from org/jruby/RubyEnumerable.java:397:in `first'