Image feature story26

Image Feature after making required changes with it's storage on server.
```js
// haven't tested this, so some details might need to be changed. 
function returnMeasurementRec(req, doc) {
  var data = doc.toJSON();
  data.images =  doc.images.map(function(img) {
    var path = '/images/' + img.idref; // using the simplified /images/abc123 path, see related comment on image.js
    var href = req.protocol + '://' + req.headers.host + path;
    return {rel: img.rel, href: href};
  });
  return {data: data};
}
```