made some major changes related to tracing and fixed some bugs along the way.

Conflicts:
	ConsoleCoreTest/Program.cs
	MongoDB.Driver.Core/Connections/Cluster.cs
	MongoDB.Driver.Core/Connections/ClusterableServer.cs
	MongoDB.Driver.Core/Connections/MultiServerCluster.cs
	MongoDB.Driver.Core/Connections/SingleServerCluster.cs
	MongoDB.Driver.Core/Security/SslStreamFactory.cs