Update dependencies + ghc 7.8 experiments.

Everything here builds under ghc 7.8 given:
  - cruncher from git
  - cruncher-types from git (hackage release coming soon)
  - snap-extras from git
  - snap-loader-static from git
  - snap-cors from git with this patch:
    https://github.com/ocharles/snap-cors/pull/3

Hopefully the above will be pushed as Hackage releases sooner than
later.