`cryptohash == 0.[456].*` fails to build with GHC >= 7.8 / base >= 4.7

[hvr]

As can be seen in https://ghc.haskell.org/~hvr/buildreports/cryptohash.html a few old major versions fail to build with GHC 7.8+ subsequently infecting install-plans with upper bounds.

The two ways to fix this, is either to

1. upload 3 point releases fixing compilation with GHC 7.8+ for the major versions 0.4.*, 0.5.* and 0.6.* respectively, or
2. edit the .cabal meta-data to add a base < 4.7 constraint to all existing cryptohash < 0.7 releases