Storing assets in Apigee

I am trying to upload assets to apigee baas for which I follow the docu in here: http://apigee.com/docs/api-baas/content/assets

Here is my code:

    var querystring = require('querystring');

    var data = querystring.stringify({
        filename: 'car_123.jpg', //asset's name on Apigee
        file_location: 'http://cdn.xxxx.com/cars/123.jpg' //asset's original destination
    });

    var target_url = "https://api.usergrid.com/<org>/<app>/cars/<uuid>?access_token=dummyaccesstokenfor_SO"

    var options = {
        method: 'POST',
        url: target_url,
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
            'Content-Length': Buffer.byteLength(data)
        }
    };

    var request = require('request');

    request(options, function(err, data) {
        if (err) {
            console.log(err)
        } else {
            console.log('success')    
        };
    });

When I run this, I get a success message. I want to believe that the image from the cdn is physically copied into Apigee. Seems that's not true

because, when I issue a GET on https://api.usergrid.com/org/app/cars/uuid?access_token=dummyaccesstokenfor_SO with header 'Accept:image/jpeg', all I get is this

filename=cars_123.jpg&file_location='http://cdn.xxxx.com/cars/123.jpg

And no base64 image string or image url.

Where am I going wrong?

EDIT: I don't see anything in the BaaS GUI either

EDIT2: As per remus's suggestion

curl -X POST -i -F name='apple-128' -F file=@"https://cdn4.iconfinder.com/data/icons/flat-brand-logo-2/512/apple-128.png" 'http://requestb.in/11xu3h61'

this results in

curl: (26) couldn't open file "https://cdn4.iconfinder.com/data/icons/flat-brand-logo-2/512/apple-128.png"

The cdn used here is just a place holder. But the result with my cdn is just the same. So, it is failing even before the POST. Makes me wonder if the file location can be a http location at all or not?