fix: unify IsImageHerokuishBased with shell version
fix: unify IsImageHerokuishBased with shell version

Really we should just spit this out into a bin and then have the shell version wrap the golang ones...

claytonbrown/dokku,progrium/dokku,dokku/dokku,claytonbrown/dokku,progrium/dokku,dokku/dokku,claytonbrown/dokku,dokku/dokku,progrium/dokku,progrium/dokku,claytonbrown/dokku,dokku/dokku,dokku/dokku,progrium/dokku,progrium/dokku,claytonbrown/dokku,claytonbrown/dokku,progrium/dokku,dokku/dokku,claytonbrown/dokku,dokku/dokku,dokku/dokku,progrium/dokku,claytonbrown/dokku