refactor: update package (#16)

Author: hoanguyenkh

internal/token/correlated_token.go renamed to token/correlated_token.go

@@ -1,7 +1,7 @@
 package token_test
 
 import (
-	"github.com/KyberNetwork/kutils/internal/token"
+	"github.com/KyberNetwork/kutils/token"
 	"github.com/stretchr/testify/require"
 	"testing"
 )

internal/token/correlated_token_test.go renamed to token/correlated_token_test.go

@@ -2,7 +2,7 @@ package token_test
 
 import (
 	"fmt"
-	"github.com/KyberNetwork/kutils/internal/token"
+	"github.com/KyberNetwork/kutils/token"
 	"github.com/stretchr/testify/require"
 	"strings"
 	"testing"