Single value field cardinality bug found in public policy

Holy heck this one took a while to fix. 

This is in regards to the public policy issue where the location field was not updating. What happened was that any text field with a cardinality set to 1 would not be updated as the feeds processor was trying to add another value but could not as there was already one there. I added a few fields to the clear out hook so that on every update they are cleared out and updated with a fresh copy from the server.