Stop using Reakit <Composite> for the station picker

[idreyn]

I originally used this component because I wanted good arrow key support in this menu — but I'm finding:

1. It's slow
2. It's forcing us to write unidiomatic React — checking data-id attributes on divs!
3. It actually breaks keyboard users' expectations of being able to tab through the list.

So let's remove it — probably we embed an onClick handler inside of <StationName> and, when that's available, use a Reakit <Button> inside of <StationName>? There may also be some aria attributes we can add to this component to retain the semantic flavor of "a list of selectable items".

Also note that when we make this change we should make the <StationName> tooltip focusable with:

  .infillStatus:hover .tooltipText,
  .infillStatus:focus .tooltipText {
      visibility: visible;
  }

[devinmatte]

This looks like in combination with #122 this could just get a quick rewrite