Downloads the Selenium Server JAR file from its
    online location and stores it locally.

def download_selenium_server():
    """
    Downloads the Selenium Server JAR file from its
    online location and stores it locally.
    """
    try:
        local_file = open(JAR_FILE, 'wb')
        remote_file = urlopen(SELENIUM_JAR)
        print('Downloading the Selenium Server JAR file...\n')
        local_file.write(remote_file.read())
        local_file.close()
        remote_file.close()
        print('Download Complete!')
    except Exception:
        raise Exception("Error downloading the Selenium Server JAR file.\n"
                        "Details: %s" % sys.exc_info()[1])