如何配置golang识别“ mod”包？

I am taking go1.11rc1 for a spin and the first thing I noticed is that goland does not recognize imports.

The goland version announcement says: "support for Go modules out of the box (formerly known as vgo)"

Anyone know how to fix this?

Problem:

1. Packages like "github.com/urfave/cli" colored red and hover text says: "Cannot resolve directory..."
2. Imported package items like "NewApp" in "app := cli.NewApp()" colored red and hover text says: "Unresolved reference ..."

Steps to reproduce:

mkdir pjg && cd pjggo.modgo mod init github.com/stevetarver/pjggo get github.com/urfave/cli

go.mod

module github.com/stevetarver/pjg/v1

require github.com/urfave/cli v1.20.0 // indirect

main.go

package main

import (
    "fmt"
    "log"
    "os"

    "github.com/urfave/cli"
)

func main() {
    app := cli.NewApp()
    app.Name = "boom"
    app.Usage = "make an explosive entrance"
    app.Action = func(c *cli.Context) error {
        fmt.Println("boom! I say!")
        return nil
    }

    err := app.Run(os.Args)
    if err != nil {
        log.Fatal(err)
    }
}

main.go

$GOPATH/pkg/mod/

Notes:

$GOPATHgo get/Users/starver/code/go/pkg/mod