V1.1.0 updates

Some long needed updates. Improves usability and leverages more of the datapoints available through the airbrake error reporting API. Includes a helper for fetching a logger object, pre-configured with an AirbrakeHandler, and many other improvements.

Updated [the README](https://github.com/samstav/airbrake-python/blob/v1.1.0/README.md) to reflect the simplified interface.
The `airbrake_error_from_record` function... I thought this was for taking a LogRecord and mapping it into a dictionary for the request? If that's the case, then we want to be able to use the notifier dictionary anytime the Airbrake class is used to report errors. If it was coupled with the log handler stuff, then calling `Airbrake().log(exception)` wouldn't get you the notifier dict. I think, if it needs to be moved so that much of the logic that builds the request body is in the same place, it should be [here](https://github.com/airbrake/airbrake-python/pull/8/files#discussion_r14510888)