…ered-by logos

… down to MenuItems

React-bootstrap Dropdowns expect that passed down props will reach
their MenuItems in order for event callbacks to be triggered (ie. auto
closing the dropdown on select).

Controlling the expanded state allows us to close the collapse after
items are selected (as recommended by react-bootstrap maintainers).

Also makes changes to the nav components to pass through props
(required by react-bootstrap to correctly wire everything together).

…ar is collapsed