haskell-packages.nix: switch default versions to aeson 0.7.x and lens 4.x

The only package remaining user of lens 3.x is the 'diagrams' package.
haskell-largeword: update to version 1.1.1
haskell-Chart: jailbreak to fix build with lens 4.x

Fixes <https://github.com/timbod7/haskell-chart/issues/21>.