Added a sitemap plugin to the generated API docs.
Created a YARD plugin that documents the services and their APIs.

This is current a work-in-progress.  All dynamic classes now appear
in the API docs, but there is no information about the available
request params and their responses.
Added yard plugin to document the API for each service operation.

Rendered documentation currently lacks a bit of helpful style to aid
readability, especially color.
Added a syntax-highlighted formatting example to each API call.
Improved the visual style and corrected the method signatures.
Updated the tab styling to look more like actual tabs.
Merge pull request #3 from aws/docs

Add API reference documentation