overriding some kcb_apt attributes

Overriding some kcb_apt attributes, as I do in the kcb_apt tests,
so we don't download the entire archive, for the test.
added a script to generate our internal apt repo from an S3 bucket of debs
adding doc about the S3 bucket, and accounting for Devon's _metadata standard
forgot to unhardcode a test case
updating documentation
latest kcb_skel filepack