Erasure Code Support for Swift

This is the first draft of the spec, lots of TODO and questions
to cover.  Not sure how it will render either, some pics included,
so will push it on up and see how it looks... also many rst
formatting errors to work through so for now please just focus
on content

Change-Id: Ic4e036317973c61fde1e524a3c7ccb255d9f4718