UUID v3 Support

[abstein2]

Adds support for UUID v3 based on the code for v5. Since v3 and v5 are generated in almost exactly the same way the major addition to this is added md5 (using crypto) and md5-browser (based on the implementation in https://github.com/blueimp/JavaScript-MD5) to the lib directory and then using them.

Updated tests, CLI commands, README_js.md, and tests. I needed v3 support for older systems as we migrate them to JavaScript.

Happy to make any additional changes.

[broofa]

This looks good, thanks! (It'll be nice to finally round out all the uuid versions in this module after all these years. :-D )

One change: v3.js and v5.js are identical but for a couple lines. Let's factor that code into a common module (e.g. lib/v35.js?) thusly ...

v35.js:

module.exports = function(name, version, hash) {
  var uuid = function(name, namespace, buf, offset) {
    ... (guts of v3()/v5() implementations) ...
    var bytes = hash(namespace.concat(name));
    bytes[6] = (bytes[6] & 0x0f) | version;
    ...
  }
  uuid.name = name; // Set function name shown in debuggers
  return uuid;
}

v3.js

var v35 = require('./lib/v35.js');
var md5 = require('./lib/md5');
module.exports = v35('v3', 0x03, md5);

v5.js

var v35 = require('./lib/v35.js');
var md5 = require('./lib/sha1');
module.exports = v35('v5', 0x05, sha1);

[abstein2]

Good idea. Updates made.