Update IAppSystem for latest DoI update.

public/appframework/IAppSystem.h

@@ -76,6 +76,9 @@ public:
 
 	// Reconnect to a particular interface
 	virtual void Reconnect( CreateInterfaceFn factory, const char *pInterfaceName ) = 0;
+	
+	// Returns whether or not the app system is a singleton
+	virtual bool IsSingleton() = 0;
 };
 
 
@@ -105,6 +108,8 @@ public:
 	{
 		ReconnectInterface( factory, pInterfaceName );
 	}
+	
+	virtual bool IsSingleton() { return true; }
 };