Support for UUID 6/7/8

[jberns88]

Would it please be possible to add support for UUID6/7/8?

Longer term it would be cool if the lib detected Ramsey\Uuid for full validation. If I find some free time I'll try and give it ago.

Thanks

[henriquemoody]

That sounds like great idea! I think it might take some time for me to implement that myself, but would you like to give it a go?