Mypaas

* Fix a bug causing ZerodivisionError on a scaled deploy if no containers for that service are currently running.
* Switch keyType to ECDSA/EC256, causing Traefik to be *much* faster (24).
* Disable really old cipher suites (25) .
* Bump Traefik version.

Note: to make use of the new keytype and prevent the use of less secure cipher suites, you'll have to run `mypaas server init` to regenerate the Traefik config files.

* A fix in the URL rule validation.

Some pretty nice improvements!

* Enable health checks (introduces a new `healthcheck` option.
* The above also allows true zero-deploy deployments when scale > 0.
* When a container crashes, a new push (with a fix) will deploy directly (previously the first next push would fail).
* Check that URL rules are not already used in other containers (which would cause the url to stop working).
* Update to newer version of Traefik.
* Add minimal example with rolling updates.

Use latest Traefik

* Mark `toml` as a dependency (it was not used on the client, but it does attempt to import it).
* Improvements to docs.

* The `itemdb` module has spun out as an independent [library](https://github.com/almarklein/itemdb), and we're now also using it as such.
* Bump version of Traefik.
* Use later version of [Asgineer](https://github.com/almarklein/asgineer).