Fixed imports

graph.go

@@ -2,6 +2,7 @@ package docker
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"os"

registry.go

@@ -9,7 +9,6 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
-	"os"
 	"path"
 	"strings"
 )