Add binaries for Elm-Test usage

I've added the elm-io binary along with its share folder. This lets people use Elm-Test to run unit tests on TravisCI, because without it you still need to use cabal to build elm-io, which depends on Elm's Haskell library.

I also added a shell script that automates most of the process and makes it simpler. You can see an example here: https://github.com/deadfoxygrandpa/HexGrid/blob/travis/.travis.yml