ivory-quickcheck requires QuickCheck >= 2.7 for Test.QuickCheck.Random

Current Haskell Platform includes QuickCheck 2.6 which isn't sufficient.
Added the formal model and proofs of type safety
Add twosComplementCast to Ivory.Language.
Merge branch 'master' of https://github.com/GaloisInc/Ivory into ivory-model-check
Merge branch 'ivory-model-check' of github.com:GaloisInc/ivory into ivory-model-check