I just added use case documents to github repo

I just added a new directory "use case" to github repo.

https://github.com/w3c/blockchain/tree/master/use%20cases

I also added a large connection of use cases I have been digesting for the last several years.

Having ran a few W3C meetings and events getting use cases into peoples hands early will help.

Erik Anderson
Bloomberg & Co-chairman W3C Web Payments IG/SG