UI: Allow all users to see all tabs, enforcing security one layer deeper

The current UI model is to completely hide/remove sections of the UI that a user doesn't have access to.  

I think we should revert this a bit and allow all of the left-hand nav links to be seen by all users (just the links) and then enforce the security one level deeper when the user navigates to the link.

This will have two benefits:

1 - Increasing the visibility of Couchbase functionality to all users (i.e., someone with query-only permissions might not know when we add a new service)

2 - Remove the need for the main UI to manage the security and visibility of future roles and services