The date displayed in the lightbox is not considering user timezone

Steps to reproduce

1. Set a different user timezone from your user profile Preferences -> Localization Preferences -> Timezone
2. Enable the lightbox feature from Administer Wiki -> Look & Feel -> Lightbox
3. Create a page, add an image to the content and open the lightbox for it
4. Compare the image date from the Attachments tab to the one displayed in lightbox

Expected behavior: the dates are the same

Actual behavior: the lightbox date is not consistent with the other dates (it uses the server timezone)