update uuidv4

Use uuidv4 generate

uid/uid.go

@@ -1,23 +1,16 @@
 package uid
 
 import (
-	"crypto/rand"
 	"encoding/hex"
-	"io"
+	"github.com/satori/go.uuid"
 )
 
-// uid returns a unique id. These ids consist of 128 bits from a
+// uid returns a v4 unique id. These ids consist of 128 bits from a
 // cryptographically strong pseudo-random generator and are like uuids, but
 // without the dashes and significant bits.
 //
 // See: http://en.wikipedia.org/wiki/UUID#Random_UUID_probability_of_duplicates
 func Uid() string {
-	id := make([]byte, 16)
-	_, err := io.ReadFull(rand.Reader, id)
-	if err != nil {
-		// This is probably an appropriate way to handle errors from our source
-		// for random bits.
-		panic(err)
-	}
+	id := uuid.NewV1().Bytes()
 	return hex.EncodeToString(id)
 }