Update building_application.md (#555)

Changed new connection to new Connection in 

```
var connection = new Connection(
    new Address("amqps://contoso.com:5671"),
	SaslProfile.Anonymous,
    new Open() { ContainerId = "client.1.2", HostName = "contoso.com", MaxFrameSize = 8 * 1024 },
    (c, o) => { /* do someting with remote Open o */ });
```

docs/articles/building_application.md

@@ -56,7 +56,7 @@ The application must ensure that the mandatory field, ContainerId, is set to avo
 
 The following example demonstrates the above usages.
 ```
-var connection = new connection(
+var connection = new Connection(
     new Address("amqps://contoso.com:5671"),
 	SaslProfile.Anonymous,
     new Open() { ContainerId = "client.1.2", HostName = "contoso.com", MaxFrameSize = 8 * 1024 },