Restore form attributes after successful upload in io-upload-iframe

Fixes #2533186
Merge branch '2533186_restore_form_attrs_upload' of git://github.com/ipeychev/yui3 into ipeychev-2533186_restore_form_attrs_upload
Uncommented tests that covers newly fixed code
Build io-upload-iframe
Merge branch 'master' of github.com:yui/yui3