Fetch the latest SDK version if 'url' is not specified. Documentation fixes.
Ensure SDK URL is usable by fetching it with an HTTP HEAD before returning
Simplify using the JSON API.
Build options in constructor so they land in installed.cfg. Recipe now updates when a new SDK is released without changing buildout.cfg.
Merge pull request #13 from olibrook/master

Fetch the latest SDK version if 'url' is not specified. Documentation fixes.