Check functionality of isPublished

[glpoulter]

I'm tempted to remove the isPublished property but I think the database uses it. Something happened when I deleted a project from the admin interface (and I'd already removed the isPublished property from the schema) I think it was removed from the project collection but not the project_cache collection or vice versa. I can't really remember what happened but I remember thinking that the easiest way of dealing with it for now is just to put he isPublished property back in to (all) schemas and sort it out properly another day!

The isPublished property would be more useful if it allowed you to save an entry before it was finished - i.e. the validity checks only run when isPublished is set to true. It's very frustrating that you can't save a partially completed entry... see #29