XFR2 form

        var formBuilder = new FormBuilder();
        blob = UserAPI.utils.dataURItoUint8Array( file );
        formBuilder.addFile( 'photo', blob );

        XFR2.send( {
            url    : url,
            method : 'POST',
            headers: {
                'Content-type': 'multipart/form-data; boundary=' + formBuilder.BOUND
            },
            data   : formBuilder.getArray()
        }, function ( res ) {
            if ( res.error ) return cb( res.error );
            var photo = UserAPI._parsePhotoHash( res.text );
            cb( null, photo );
        } );