Date Matching when 3rd and 1st are used

I often receive letters where the date format is:
23rd December 2013
I scan in via a Scansnap 1300i
How do I set up content matching to handle the rd or st please?
I would like to rename the files: YYYY-MM-DD
23rd December 2013
I scan in via a Scansnap 1300i
How do I set up content matching to handle the rd or st please?
I would like to rename the files: YYYY-MM-DD