Web properties should have similar high-level navigation

The existing Web properties are largely disconnected, but should be cross-linked

- Home page / blog
- Fusion language docs
- Java API docs
- Playground

I’d like to aim for common masthead with shared high-level navigation, but at the very least one should be able to traverse across the major components.  At the moment it's easy to get dead-ended with no way back to the home page.
