newly created router briefly reports as ACTIVE before it is built

[Adam Gandelman]

When a new router is created, it briefly reports as ACTIVE before it it starts to be built, causing pseudo-script like this to fail:

router=create_a_router()
wait_for_router_to_reach_state(state='ACTIVE', router=router['id'])

The first few passes of a wait loop will pass thinking the router is active, but it then switces to BUILD and continues on building as normal. This is not ideal and confusing, we should see if this can be reported accurately.