init godep
Add godir per docs

See doc comment here:
https://github.com/docker-library/golang/blob/af4e450a47a99f9a4f56225cdf
598f552907d946/1.3/wheezy/go-wrapper#L14

Gist is that .godir acts as an aid to the Docker build script such that
paths are correctly mapped
Switch to image golfing:1.3.3 instead of onbuild

I want to use godep for dependency management, so removing the onbuild
Docker image so that I can build via godep
Update docs w/ some basic setup
Add a simple test
Comments for clarity