Changed to a more appropriate exception type

As recommend by @gmarz changed from a generic exception to a transport
type exception.

Author: eddyzanda

src/Connections/Elasticsearch.Net.Connection.Thrift/Transport/TSocket.cs

@@ -117,14 +117,14 @@ public override void Open()
 			{
 				InitSocket();
 			}
+
 
 		    var connectionRequest = client.BeginConnect(host, port, null, null);
-		    
             var connected = connectionRequest.AsyncWaitHandle.WaitOne(timeout);
 
 		    if (!connected)
 		    {
-		        throw new Exception("Failed to connect");
+                throw new TTransportException("Failed to connect");
 		    }
 
 			inputStream = client.GetStream();