Async trigger behaviours are not included when calling GetInfo

Async trigger behaviours are not included when calling GetInfo, resulting in incomplete graphs.
In the following snippet, `stateMachineInfo` will not contain the transition from A to B.

``` csharp
var sm = new StateMachine<State, Trigger>(State.A);
sm.Configure(State.A)
    .PermitIfAsync(Trigger.X, State.B, () => Task.FromResult(true));

var stateMachineInfo = sm.GetInfo();
```