Peter/routing pager

https://github.com/mapzen/on-the-road/pull/23
-Fixes routing paging so it adjusts colors and icon as routing is in progress.
this method and it's opposite method can either be in the route adapter and called from the route fragment orin the route fragment and the adapter can grab what state it should be in. The route adapter can't keep an accurate account of what state it should be in so the route fragment needs to do that. Which one do you think is better?