Fix project root bug

[joncol]

This solves a bug where no project name would get reported when using harpoon with project.el.

[ptillemans]

These patches also fix issues on windows where the project root is not properly recognized and removed from the file when using in Windows.

[joncol]

@otavioschwanck: Any chance you're looking at this?

[otavioschwanck]

@joncol could you resolve the conflicts?

[joncol]

@otavioschwanck, done.