4179 - Update wording of "invitation to claim" email

This update is to correct the instructions for updating a redirect: the user should delete the imported copy before contacting Open Doors, and to replace a "stories" reference to "works".

https://code.google.com/p/otwarchive/issues/detail?id=4179
I think there's a stray ) after the Open Doors contact URL: `contact Open Doors at http://opendoors.transformativeworks.org/contact/open%20doors)`