Actual Behavior

It is not possible to modify the date of creation of an entry/post. (publication, event, announcements)
Safari doesn't display the creation date/time when editing an entry in the sulu admin-page, it only shows "NaN.NaN.0NaN NaN:NaN". In the edit-modal however, only the timepicker is not working and shows "NaN:NaN". The datepicker is fine and the date is displayed correctly as well. However it is not possible to save the entry because JavaScript is crashing.

• This issue only occurs with Safari

Expected Behavior

The entry (event, publication, announcement) can be modified.
Date and time is displayed in the admin-page and edit-modal.

Steps to Reproduce

0. use Safari and log in as administrator
1. Go to Content
2. edit a single Entry (publication for example)
3. Go To the "Settings"-Tab
   -- on the bottom of the page, you can see the first error regarding "NaN" when you take a look at the changelog --
4. Click the edit-symbol in the Changelog
   -- in the edit-modal you can see the "NaN" on the right side at the timepicker --
5. Click OK and try to save the Entry