New home for GoLLVM

Hi folks,

Cleaning up the API of GoLLVM has been on my mind for a while. I've taken
the first step, and moved it to a new home: http://github.com/go-llvm/llvm.

If you're using github.com/axw/gollvm, then it'll continue to work - I
moved and forked it back there with the existing API/directory structure.

If you do migrate over, then be aware that I intend to make API breaking
changes. When I'm happy with it I'll create a v1 branch so you can use a
gopkg.in path. Keep an eye on the repository on GitHub if you care about
that.

Cheers,
Andrew