This PR groups the contents api endpoint with both `""` and `/*` as
valid URL patterns.
When `""` is the URL pattern, this means that no repo path has'nt been
provided, in which case the path would be the default repo path.
When `"/*"` is the URL pattern, then this would return the contents at
the specified path if it's valid.
Github API v3 is conformant to this behavior and have verified it
locally.