send width and height to the api-server

[yuhengd3]

#190

[mjumbewu]

@yuhengd3 What would you think about moving this into a separate function -- something like:

annotateWithAspectRatios: function(attachments) {
  var i, a;
  for (i = 0; i < data.attachments.length; i++) {
    a = data.attachments[i];
    a.ratio = 100.0 * a.height / a.width;
  }
},

Then from we could just call that from here:

this.annotateWithAspectRatios(data.attachments);