Add color to the prices if past prices exist

Add green/red colors to the current price if a past price is
above/below the current price.
Provide way to update tracked item

Supply the ID for the tracked item in the controller, so that each
model can be built with a tie to the underlying tracked item.  Add a
PATCH API to tracked-items-ui to allow updating of the name.  Implement
the basics of the view item details in the UI.