fix: throw exception when push has been rejected

[mgabelle]

Intrpduced variable :

    private static List<RemoteRefUpdate.Status> REJECTION_STATUS = Arrays.asList(
        REJECTED_NONFASTFORWARD,
        REJECTED_NODELETE,
        REJECTED_REMOTE_CHANGED,
        REJECTED_OTHER_REASON
    );

We check the result of each push (it was not the case before).
If the status of the push is in one of the rejected state above we throw an error and stop the push
#88