making renaming clear card cache for old name

Ticket

+commit
 

when you rename a card, the old name still retrieves a card.

 

guessing it's easiest to make renaming just wipe the card entirely.

 

as of now, it's still happening here:  http://www.connectipedia.com/wagn/Lane_County%2C_OR+general_info_from_county

 

("general info from county" doesn't exist, it was renamed to "state general info from county")

 

This was happening on Some_punctuation_breaks_search+example, which John changed to be the example on a different ticket.  In that case, things were breaking (something to do with a type call on the nonexistent cached card).