message: reduce thumbnail size
  use jpeg 30%
diff: @@ -122,7 +122,7 @@ jsxc.Message.prototype.save = function() {
  ctx.drawImage(img, sx, sy, sWidth, sHeight, 0, 0, dWidth, dHeight);
  - this.attachment.thumbnail = canvas.toDataURL();
  + this.attachment.thumbnail = canvas.toDataURL('image/jpeg', 0.3);
  if (this.direction === 'out') {
  // save storage
  