DLNAOrgPN description in renderer conf

Useful for troubleshooting. Maybe for even better troubleshooting we can set it to something special so e.g. file will be displayed on renderer in more variants with all the PN types what exists so user can easily test which file works and post results so we can update renderer confs or UMS code directly. Similar thing I did in my debug version for "DLNA.ORG_OP=??" so I was able to test what PS3 or my PanTV like or dislike.
http://www.leidinger.net/blog/2011/09/15/sony-bravia-tv-dlna-formats/
Merge pull request #79 from ExSport/patch-2

DLNAOrgPN description in renderer conf