Such that the `get_hist()` query func raises `DataUnavailable` with an
explicit message regarding the start of the (option) contract's
lifetime.
Other,
- mask some unused imports (for now?)
- drop a duplicate `tractor.get_console_log()` call which was causing
duplicate console emits (it's already setup by brokerd init now).
- comment various unused code bits i found.
- add a info log around live quotes so we can see for the moment when
they actually occur.. XD