fix images 'AllPages' paging (#266)

* fix images AllPages paging; make AllPages more robust

* need to keep using the local page when iterating in AllPages
diff --git a/openstack/imageservice/v2/images/testing/requests_test.go b/openstack/imageservice/v2/images/testing/requests_test.go
index 788eec4..fdd8402 100644
--- a/openstack/imageservice/v2/images/testing/requests_test.go
+++ b/openstack/imageservice/v2/images/testing/requests_test.go
@@ -44,6 +44,19 @@
 	th.AssertEquals(t, 3, count)
 }
 
+func TestAllPagesImage(t *testing.T) {
+	th.SetupHTTP()
+	defer th.TeardownHTTP()
+
+	HandleImageListSuccessfully(t)
+
+	pages, err := images.List(fakeclient.ServiceClient(), nil).AllPages()
+	th.AssertNoErr(t, err)
+	images, err := images.ExtractImages(pages)
+	th.AssertNoErr(t, err)
+	th.AssertEquals(t, 3, len(images))
+}
+
 func TestCreateImage(t *testing.T) {
 	th.SetupHTTP()
 	defer th.TeardownHTTP()