it is no longer feasible to build the blueprintjs css ourselves, so we
just use all of the default variable values and override things using
selectors instead.
This adds an indicator to the status bar that shows the hub name. When
clicked, a popover will be displayed that lists more detailed information
about the connected hub.
This adds custom styling for the toolbar (inspired by blueprintsjs
navbar). But this lets us use the correct role and not fight the
navbar styling so much.
David Lechner