base64x updates et.al.

• base64x.js
  • KJUR.lang.String class added and its some static
    methods isHex, isInteger, isBase64, isBase64URL and
    isIntegerArray also defined.
  • KJUR.lang added to npm package namespace.
• tool_string.html added to provide string converter tool.
• jws.js
  API document updated.
• CryptoJS codes in code.google.com seem to be removed and
  404 not found so that CryptoJS references in all test
  were moved to local files.
• CryptoJS codes were moved to ext/cj directory.
• tool_b64u{enc,dec}.html script URL fix