Implemented ShouldRenderFile

Please review.
> While we are at it let's delete that method we marked [Obsolete] at the same time

That is some good thinking man - done.

> Also, having a readme.txt file in the root package will pop it open - we can include mention of the breaking changes file and other files like I've done in ChameleonForms:

So I added a `readme.txt` to the package root but I have some questions:

- Should I link the `readme.txt` between both projects?
- Could you please direct me on the exact path to use in the NuSpec? Looks like `<file src="readme.txt" target="" />` is correct but I am not sure.