Fixing invalid gocart url

Was failing with:

$ go get -v github.com/xoebus/gocart/gocart
github.com/xoebus/gocart (download)
package github.com/xoebus/gocart/gocart
    imports github.com/xoebus/gocart/gocart
    imports github.com/xoebus/gocart/gocart: import "github.com/xoebus/gocart/gocart": cannot find package