add safe url Base64 codec

[det101]

    var message = "https://github.com/";
    var key = "u-rXsMB_aegAnzC_CJt27plLGNqOfR2EHI5o2ro1NOI";
    var baseKey = CryptoJS.enc.Base64.parse(key, true);
    console.log("key："+baseKey.toString());
    var hash = CryptoJS.HmacSHA256(message, baseKey);
    var hashInBase64 = CryptoJS.enc.Base64.stringify(hash);
     console.log("result", hashInBase64);
    var shashInBase64 = CryptoJS.enc.Base64.stringify(hash, true);
    console.log("safe result："+hash.toString())
    document.write(shashInBase64);

issue #252
fixed #252

[evanvosberg]

I do understand the goal this, but I would not modify the existing enc.Base64 module for. I would rather prefer to create a new module named enc.Base64url.

[evanvosberg]

Dedicated Base64url encoding has been added in the 4.1 release.