convert route endpoints to new lookup API

[davepacheco]

This change updates the "route" endpoints to use the new lookup API.

As part of this, I changed the router_id column on the router_route table to be called vpc_router_id, so that we can maintain the expectation that the foreign key id is derivable from the foreign table name. #798 depends on this.

[davepacheco]

I think this is ready to review but it's blocked on #798.

[david-crespo]

Looks great. Kind of funny that it's more code, but it's very nice code. And deleting vpc_router_lookup_by_path eventually will offset it.

[davepacheco]

Yeah, I'd forgotten to remove vpc_router_lookup_by_path. It's less code now!

[david-crespo]

oh right, we can remove the hand-written database functions now

never mind about it being more code!

[zephraph]

This is just sooo damn good.