FIX #58: Added logging facilities

* Use standard python's logging lib.
* Log http-request/response/errors.
* Cmd-line options for logging-format and filename.
* Cmd-line options for request /response/error requests/responses/errors
props to log.
* Add `-v` option controlling verbosity.
* Add docs about new options.
* TCs for only logging options (logging statements used throughout all tests).