GHC 7.8, cabal-install 1.20.0.0

* Fresh versions of required external libs
* Properly exposes the lib include files
* [outside these commits] Added prebuilt versions of all libs to S3
* [outside these commits] Added prebuilt binaries for GHC and cabal to S3
* Fixes #47 (just needed newer libs and the problem went away)
* @rehno-lindeque can you check if this has addressed #42?
* I *thought* this would have solved the relinking in #12 but somehow it hasn't. See http://blog.johantibell.com/2014/04/announcing-cabal-120.html#unnecessary-re-linking-avoidance

Anyway...yay!