Add total_commits per author to git.receive notification
    
    Currently, Fedora Badge "Long Life to Pagure" does not function
    correctly. The issues it has are described at
    https://pagure.io/fedora-badges/pull-request/806
    
    One of the issues can be solved by simply making Pagure's git.receive
    notification list commit count per author. Exactly that is added here.
    
    The notification schema is only changed by adding a new field, which
    should be non breaking.