Change Directory Resolver to support Dependency Injection (IOC)

[aabragan]

It would be really neat to be able to plug in your own directory resolver through the Resolver Factory. I use PortableAreas in MVC and wrote our own VirtualPathProvider implementation. I would like to be able to plug the same directory traversal logic into Squishit without having to build a custom version. I am happy to work on it and add it in if needed.

[AlexCuse]

I could see this being useful - If you want to submit as a pull request I will take a look.

Look at the Configuration class to see where we currently manage things like this (Bundle.ConfigureDefaults() returns a static Configuration instance). It is getting to the point where it needs to be cleaned up a bit but it shouldn't be too painful to figure things out from there. The DefaultXXX methods are the ones used to retrieve instances where needed.