Refactor TestCopyDataToPersonFormEventTree.py

TestCopyDataToPersonFormEventTree.py had some whitespace issues (mixing
tabs with spaces). I also removed the import hack as we now know better
python practices.
Add test showing formImportedFieldName is required

It's *supposed* to be optional, but formImportedFieldName is treated in
the code as required. This is probably because for the Pilot Project,
all our forms have imported fields.
Remove implied assert of a formImportedFieldName