MBS-6269, Output track identifiers in XML output.
Merge branch 'master' into mbs-6269

* master:
  We require postgresl 9.1.
  MBS-6295, move use Test::JSON line up.
  MBS-6295, Track identifier related changes in relationship editor.
  MBS-6293, Update /ws/1/ track lookup by puid for track identifier changes.
  MBS-6271, construct correct /cdtoc/set_durations url.
MBS-6269, Output track identifiers in JSON output.
Merge branch 'mbs-6269' into beta

* mbs-6269:
  MBS-6269, Output track identifiers in JSON output.
  MBS-6269, Output track identifiers in XML output.