Include DDSec example solutions

[bramcordie]

I attended the DDSec workshop at DDD Europe where we used this app to discuss how domain driven design can help secure the application.

I think all the vulnerabilities that are mentioned in the README were discussed but I'm not sure if we covered all the possible solutions. I can fork the project to implement my own solutions but it would be nice to have reference included with the project.

If you don't want to make them too obvious, you can obscure them by putting them on a separate branch?

[danberghjohnsson]

There are some possible solutions crafted, but they have not made it into the repo yet. They will probably end up as a branch, or several.