add editing mode for storyblok integration

[thomaspink]

• [ ] Check if we are in edit mode (running in an iframe, ping parent frame and listen for ping back, see code blow)
• [ ] Reload active stories in draft mod
• [ ] Make sure to not cache stories with draft version (always load from the server)
• [ ] Append markers (comments, field _editable) for storyblok

pingEditor: function (cb) {
  if (window.location != window.parent.location) {
    window.parent.postMessage({
      action: 'ping'
    }, this.parent())
  } else {
    this.inEditor = false
    cb(this)
  }

  this.on('pingBack', function () {
    this.inEditor = true
    cb(this)
  }.bind(this))
}

events: {
  'change': [],
  'published': [],
  'unpublished': [],
  'viewLiveVersion': [],
  'enterEditmode': [],
  'pingBack': [] // THIS ONE
},