[ghc-steering-committee] Backpack, complete spec

[Christopher Allen]

https://github.com/ghc-proposals/ghc-proposals/pull/5#issuecomment-280942000

Could I get a quick up/down on this?

I'd rather not start making exceptions to the process we laid out. If
a proposal is so complicated at the proposer cannot gather a complete
specification of the proposal, it should under no circumstances be
checked into source control.

-- 
Chris Allen