fix 'job_url' and 'group_url' keys in messages
    
    The 'job_url' key is supposed to appear in messages when a result is
    created using API v1, but this regressed in commit
    62c49f7fac88d88c954dccbb2a532e9f67b82faf which introduced API v2. The
    create_fedmsg() function was still referring to the `result.job`
    attribute even though it had been removed from the model in that commit.
    This patch restores the previous intended behaviour for API v1 messages,
    with a test case.
    
    The 'group_url' key was introduced in the same commit as an analog when
    results are created using API v2, but this also never worked because of
    a typo: it was referring to a `result.group` attribute but the model
    actually has `result.groups` (plural). The same typo was carried over in
    commit fd4ebfb0e8389931213acc9eefc40d07e158d30a ("flexible messaging").
    Since this never worked, and thus the 'group_url' key has never been
    included in any messages, this patch simply drops it.