mark as paid link no show page uses ajax

- updates 'mark as paid' and 'edit' buttons to
  be disabled
Marking as paid on claims page displays date paid on

- add claims serializer
rename function which makes mark paid ajax call
add error text on mark as paid failure
no longer pass link into updateshowpageafterpaid
use let instead of let! in claim serializer spec
Merge pull request #2 from gpallotta/ajax_mark_as_paid

Ajax mark as paid