bump Go to 1.4

This bumps the Go version to 1.4.

Please note that this version of Go breaks gosqlite and it also breaks mattn/go-sqlite3 when used with Docker.

This PR is also meant to be the place where we discuss everything related to this bump.
I wish we could get something official telling us that this really is "the new official way" and that this isn't going to break on us in 1.5 or 1.6. :cry: (I guess that'd have to be in the form of an integration test upstream.)