add http "header" support to $media.play

[darenr]

I don't see in JasonMediaAction.m any use of @"headers" which explains why it doesn't work when I add headers in my markup. It would be great to be able to use "header" (or better yet, "http_headers") anywhere that "url" is valid.

"action":{
   "type":"$media.play",
   "options":{
      "url":"{{video['mp4']}}",
      "header":{
         "referer":"http://whatever.com/"
      }
   }
}

possibly useful: stackoverflow