Log Message:
Update ruby-zip to 1.2.1.

v1.2.1

* Add accessor to @internal_file_attributes #304
* Extended globbing #303
* README updates #283, #289
* Cleanup after tests #298, #306
* Fix permissions on new zip files #294, #300
* Fix examples #297
* Support cp932 encoding #308
* Fix Directory traversal vulnerability #315
* Allow open_buffer to work without a given block #314