moved fill to its own header - so interfaces could cleanly include
added persistence of fills
more enhancements to submit logic in the book
made some changes to bootstrap_scenario_1 to make it more interesting
added transient timestamp to submit_request - server sets timestamp when processing requests. timestamp does not come from client, but is persisted in dsv serialization.
implemented halt command
added log command
added exchange_config (maybe YNGN but used in dev to conditionally measure performance impact of not publishing responses)
added some tracking of market stats
Merge pull request #3 from patefacio/master

order book management work, halt command, log book