Introduce services as "sub projects"

[niknetniko]

For example, each part of the Hydra API (resto, schamper, ...) could have it's own status.
There should be a way to either add subprojects or group projects together.

A project can have multiple services, which are the entities that will actually perform the health checks. The status of a project would then be the worst status of any of its children.

Not very relevant, since use will be low, but we need to think a bit about the GUI, preferable keeping our simple HTML forms, without any of that fancy javascript stuff.