Deduplicate list of contributors
    
    It is possible the same person commits into a repo with multiple
    identities. Pagure already can be told about multiple e-mails for a
    single person. This patch checks if the address in the commit is known
    and possibly replaces with the default e-mail.
    
    If the e-mail is known, the name is also replaced with full name of the
    user.
    
    Records for contributors not known to Pagure are presented as before.
    
    The page showing commits for a single contributor already displays all
    of them no matter what identity was used.