RFE: stand-alone API

[isimluk]

Currently SCAPtimony is used inside a foreman_openscap. Foreman_openscap exposes REST API and uses its own authentication mechanism for this API.

We could put the common pieces to SCAPtimony and then there would be SCAPtimony-server package that would allow to run SCAPtimony as a separate/independent microservice. The foreman_openscap and scaptimony-server should share the API code then.