2.5.x features

shows, show-schedules, show-preview, show-history-feed, item-history-feed endpoints to the HTTP api to be used via NewscoopAirtimePlugin

These endpoints are needed for airtime pro instances and should be merged to saas branch.
It looks like getPlayedItemData() has a bug where custom fields don't get serialized properly. I added a custom boolean field called "Canadian" to my play history template and look what it got serialized as:

{"starts":"2014-11-19 19:08:25","ends":"2014-11-19 19:10:00","history_id":35,"instance_id":36,"track_title":"Grand Canyon","artist_name":"Kavinsky","fozjsscozz":false,**"checkbox":""**}]