check latest version from sonatype and warn user if update is available

It will do a get to github api and parse the json response to get latest version. It then compares it with current version and prompt user for update if applicable.
It will not work because that recursive function returns a number to indicate comparison result. Once `set -e` it will treat it as error status code and terminate. I think I've tried to rewrite it to return string but not successful. My bash programming knowledge is not enough.