function displayProgress(statusObj) {
        statusObj.spans.forEach(function (span) {
            if (span.id === 'percent') {
                var bgColor = $('#status-bar').css('backgroundColor'),
                    bgval = 'linear-gradient(to right, #1474BF ' + span.val + ', ' + bgColor + ' 0%';
                $('#update-status').css('background', bgval);
            }
        });

    }
Displays the progress bar on Status bar, while the download is in progress
@param {object} statusObj - json containing status info - {
                          target - id of string to modify,
                          spans - array of objects of type - {
                          id - id of span for modifiable substring,
                          val - the new value to modifiable substring }
                          }