recodring_url exposed in cdr_summary

It will be nice to see if recording_url exists and call was recorded from cdr summary without querying for details on each CDR. I'm not sure where is the view file to update database view and include revording_url. I'm not sure if that's required. 
since recording_url is in custom_channel_vars is there a need to include this in the cdr schema ?
besides that, taking into account that normalize_cdr isn't at this moment flexible enough, i'm ready to accept this pull request.