Introduce a Global Loading State

[dshoreman]

When the page is initially loaded, there shouldn't be any application UI visible until the user's profile has been loaded.

Instead, the main container should have some loading state that replaces its contents with a placeholder of some sort.

Additionally, all AJAX requests that require auth should be held off until the initial profile response is received. This should reduce the 401s for things like the system stats quite a bit.