add sdk download impl

liuxiaolong

2020-06-08 2a4041f16c6588921c87df93927e9076c2cc309d

 extend/util/requtil.go

@@ -3,8 +3,8 @@
import (
   "bytes"
   "encoding/json"
   "fmt"
   "github.com/ajg/form"
   "golang.org/x/tools/go/ssa/interp/testdata/src/fmt"
   "io"
   "io/ioutil"
   "net/http"