WIP: Initial implementation of project resource

This PR is intended to show the community an implementation approach consistent with #1017

Yeah, I misunderstood this file completely yesterday, sorry-- at home with a cold and not firing on all cylinders.

I'm actually not a fan of this approach, we shouldn't bake the notion of "project" into apiserver, which is generic.

Instead, I'd prefer to see something like a Policy interface in the apiserver package. Enforcement of project scoping is just one policy, it should be implemented elsewhere, and injected when the master creates its apiserver.

```
type Policy interface {
  Allowed(userIdentity MissingConcept, verb, resource string, obj interface{}) (bool, error)
  // If we want to present projects at different places, I can imagine something like this:
  RewritePath(userIdentity MissingConcept, externalPath string) (internalPath string, err error)
}
```

That's just an example, I haven't thought carefully enough about it. It should probably line up with @erictune's policy object, in the security proposal. I'd actually prefer to see that in a different PR. It's OK if this PR just adds the Project resource type and doesn't wire it in. In fact that's almost mandatory because we need a user identity concept before we can do enforcement. IMO.