Fix playlist duration handling
Fix playlist duration handling

The duration returned after parsing the playlist is just the string in the
file. Using totem_pl_parser_parse_duration we get the value in seconds.

outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker