Improve Inspec to NIST 800-53 Mapper Abstractions

[tohch4]

Fixes #3.

[gregelin]

Looks very good!

[aaronlippold]

also, the name control_id for the nist control may be confusing.
I would suggest we use something like nist_control to be clear as inspec using the term control id as part of its schema.

[tohch4]

also, the name control_id for the nist control may be confusing.
I would suggest we use something like nist_control to be clear as inspec using the term control id as part of its schema.

I can agree it's confusing, but I was trying to explain it from the perspective and shape of Inspec data, maybe that is a little misguided. I was thinking of something like tag_filter or control_family_tag to make it clear "what" in Inspec maps to "what" in OSCAL. Would love more feedback like this. Keep it coming!