merge wiki contents, content edits


@johnwunder This branch won't auto-build or change production until merged to master.

- merges gh-wiki content in
- compatibility with github pages jekyll layout (i.e. can be directly dropped in the stix.github.io repo and generated)
- minor edits for formatting and clarity
- fixup links
- comments in md where I didn't understand content

The two components I didn't touch are the generation of code documentation ( which I basically commented out) and the bootstrap css. The former I would recommend transferring to RTD, and defer to you on how that works. 

The latter I just didn't want to change since the amount I know about CSS could fit in a thimble. Probably makes sense to create a standard navbar across the projects, and not use bootstrap unless there's a compelling reason to do so (i.e. use the builtin template instead)

-_Ben