[874] Fixed the package editing form to avoid overwriting contact details

There are still a few issues that might need thinking about.

* If the user edits the contact details, decides that they don't like the edit and then clicks the close button, if they click edit again they will get the dialogue with the edits from before.
* The contact details are inherited from the publisher at edit time, so if the contact details of a publisher changes all of the datasets will keep the old contact details.