Add libswarm Makefile

This is a pretty simple makefile but it gets the job done in that it'll go snag dependencies, wire up the build environment as go expects it and then build the code. I decided against using godep for now; it won't be on many user systems by default. I'm considering making a separate makefile for godep (since we can skip any kind of workspace generate with it) but for now I think this will do.

Signed-off-by: John Hopper john.hopper@jpserver.net

You know, If you do `go get` instead `go install` it is the same, but with automatic dependencies download.