Before, a completed street was associated with the first activity that touched it. 
Now, a completed street will be associated with the last activity that touches it. 
I also went through the existing completed streets to re-associated those to the latest activity.
This has a little odd side effect where you might see a completed street move to a later activity. This is because the site might have marked it as complete (you finished more than 90% of it), but then you ran a little bit more of the street later on.
