WIP - first draft of intro, part of the rest basics chapters

Rough drafts on a few chapters, up for technical review:

1) intro chapter
2) REST basics chapter
3) POST
4) GET
5) Testing (WIP, so don't check out yet)

I think I may have overdone the theory in REST, and it would be better to not introduce this stuff (or only *very* briefly) here and introduce it piece by piece as we actually get into the items. Thoughts?

Thanks!