Remove pathname require from ruby_project.rb

Achieved by implement ascend simply ourselves.
Did you conclude that it's not actually possible to have escaped slashes in path names?  Or just that you haven't figured out how to solve it yet?

BTW, for future reference, while I like `xit` for a quick way to make something temporarily skipped, I much prefer committing code with `:pending` for a few reasons:

* It's much more explicit; `xit` doesn't have an obvious meaning to someone who hasn't seen it before.
* Using `:pending` allows you to attach a descriptive reason.
* Pending also is more robust in the sense that it will notify us if the example starts to pass.