Add job information retrieval

:rotating_light: WIP :rotating_light: 

I'm submitting this as a WIP to get feedback and to elicit discussion about the overall architecture of the code.

1) The HTTP callback business has to go.
2) Retrieving the authentication information before each HTTP call is annoying.
3) The global hash map makes for an awkward api (Ref #https://github.com/AshtonKem/Butler/issues/11)
4) Pertaining to 2+3, maybe some kind of proper object (defstruct?) could be used for better access to relevant information?

As for the code in this PR -- please review. I want to provide a better view of the actual job data, opinions welcome there.

Questions:

Should the information query automatically query the last 10 or so jobs (each a new HTTP request!) or not? Is there a way to get this information in one go?