[REVIEW] Make controller instantiation customizable

[Greg Brown]

> But what Dan wants to do is to go from a string to an instance using a DI lookup, not from a string to a class to an instance. How does the combination of ClassLoader + ControllerFactory solve that?

Can you be more specific? In other words, how does using a type argument vs. a string argument not permit that? I'm no expert on DI, but I know that we had a similar requirement in Pivot (developers wanted to use Spring and Guice to instantiate controllers) and a Class was sufficient in both of those cases.