Export of Spec_Items Hold Empty Tables

[pasetti]

When I look at a project which has been exported and then re-imported, I see that the s_data field of the spec_items is set equal to "{}" (with the quotation marks). The correct value should be: {}. This confuses the list_spec_item template which interprets the entry as a non-empty table and displays it.

[pasetti]

While looking at this issue, I realized that if the user leaves the s_data field empty, there is an exception. I have added a check for this purpose in the clean_s_data method in forms.py.