GitHub https token (#1)
GitHub https token (#1)

* Add support for Github HTTPS with token

* Use :scm_user instead of :scm_username

* Remove debug logging

* Fix conditional

* Simplify repository gsub

Co-authored-by: John Williams <a51dda7c7ff50b61eaea0444371f4a6a9301e501@basecamp.com>
basecamp/cached_externals,basecamp/cached_externals