Log what's going on at ct-server startup

[robstradling]

Al wrote in an email to me:
"Note that depending on how many entries are in the tree it can take a long time for nodes to restart as they scan the entire local db to verify it and rebuild the node's merkletree and indices. Sadly there's no logged message to indicate it's doing this, someone should change that, but you'll see the CPU usage pegged high while this is happening."