nav_stats for new map type

[gpdas]

What is the plan for nav_stats for toponav2? Will it be available?

Oxford's coordination work depends on finding some distributions from nav_stats from mongodb. These distributions will be required for probabilistic congestion aware route planning.

[gpdas]

Existing logger is still available in this script. This logger node needs to be started for logging navstats.

Now uses message_store