Add ownCloud and Known

Added a README file to per-user/wordpress, per-user/owncloud, and per-user/known, so that they can be run using only Docker, and without depending on `systemd`, `etcd`, and `cloud-config`.

The ownCloud and Known images are now both to the point where they build successfully and you see the first-time-use page on http://localhost:80/ when you run them according to their README.md files.

But at least ownCloud (and probably also Known) still has some bugs to fix before this can be merged.