status driver

see https://github.com/inaes-tic/mbc-mosto/pull/54 for some comments

This code is coupled with caspa's handling code (it says so in the comments) and some of it should be moved to mbc-common and implemented as backbone models.

Nonetheless, it works and is not *extremely* ugly. I'll work on migrating to mbc-common on a new branch based on this tip

here's a description of the status messages this expects. 

        /*
          meltedStatus = {
              clip: {
                  previous = position in list
                  current = position in list
                  next = position in list
              },
              show: {
                  previous = Playlist
                  current = Playlist
                  next = Playlist
              }
              position = playback % of current
              clips = [clip list]
          };
        */