Updated theme_fundraiser_credit_card_expiration_date() to preserve the main element's #title.
Added a title to the main cc expiration_date field in _fundraiser_commerce_credit_card_form().
Merge pull request #419 from JacksonRiver/7.x-4.x-fundraiser-cc-expiration-label

Fundraser CC expiration date field title doesn't need to be hardcoded twice.