Add support for fetching files to root track dir

[kytrinyx]

This depends on work being done in the API:
https://github.com/exercism/x-api/issues/27

See exercism/php#11 for context.

[ErikSchierboom]

This would be great to build/test scripts, which people tend to expect in the root directory.

[ErikSchierboom]

@kytrinyx Should the on-hold status be removed, due to this PR being merged in the x-api repository? As you can tell, I really want this feature :)

[kytrinyx]

Yessss! This is ready to go now.

[ErikSchierboom]

🎉

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[kytrinyx]

Replaced by a more well-defined issue:
#388 388