Adding keepdefaultrules option by means of a directory passthrough

See merge request !59



Merged-by: Vishwa Bhat <vbhat@gitlab.com>
Approved-by: Adam Cohen <acohen@gitlab.com>
Approved-by: Vishwa Bhat <vbhat@gitlab.com>
Reviewed-by: Vishwa Bhat <vbhat@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>
Co-authored-by: Julian Thome <jthome@gitlab.com>
Co-authored-by: Adam Cohen <acohen@gitlab.com>