This is mostly with the intent of making the login tests more reliable, but it
seems generally worthwhile:
* keep screenAfterLogin in the object props rather than `state` so that we can
clear it without triggering a rerender
* also move our record of the window width to the object props, and call
`handleResize` from componentWillMount rather than componentDidMount so that
we don't trigger a rerender by updating `state.width`
* Remove update of unused `loading` state
Richard van der Hoff
38114711fd