RabbitHutch comments update

* EasyNetQ.CreateBus(string connectionString) and EasyNetQ.CreateBus(string connectionString, Action<IServiceRegister> registerServices) were mentioning that, if not specified, the default
requestedHeartbeat would be 0. This is incorrect, the default value is set in EasyNetQ.ConnectionConfiguration ctor “RequestedHeartbeat = 10;”
* Fixed some '&lt;' and '&gt;' characters (probably the result of a former conversion), now using proper curly brackets to designate generics in comments.