Making the whole thing work play nice under chroot

- Adding 'Serialize' instance for 'Data.Text' in 'Display'
- Verbosity settings hardcoded (TODO: Move to EvalSettings)
- addPkgDb function that adds a custom package database
  (currently hardcoded)
- Proper chroot call (using saved user id and euid)
- The user code is now being sent through the socket rather
  than being written to a file

Bootstraping should be performed like this:

- deboostrap
- mkdir -p ./home/vagrant in the bootstrapping dir
- mount --bind in ./home/vagrant
  - ~/.ghc
  - ~/.cabal
  - ghc (ghc installation dir)
- copy Helper.hs to the jail root
- chroot && apt-get install gcc