Rewrite to use TogoWS REST API instead of SOAP-based KEGG API.

 * Rewrite to use TogoWS REST API instead of deprecated SOAP-based
   KEGG API.
 * Examples are changed to fit with current TogoWS.
 * Now, the script does not depend on any non-standard libraries
   including BioRuby. This means that one can put this script on
   a server without installing BioRuby.
 * New constans SCRIPT_NAME and BASE_URL for easy customizing.
 * Many changes. See "git diff" for details.