Fix issue #4, allow multiple paths in GOPATH

Thanks for providing a very nice tool! The only issue I ran into was that it did not have support for multiple paths in GOPATH, something which I'm using extensively.

As a side note, I'm running sublime with GoSublime which runs `go fmt` on each save. This made the contribution this this repository a little more difficult as the delta became huge. Please consider running `go fmt` on your code as this is the convention used by most project in the Go ecosystem.

Cheers /u