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.
I would like to see this refactored into code like:

    err = airbrake_error_from_record(record)
    self.airbrake.notify(err)

where `airbrake_error_from_record` constructs dict in format expected by Airbrake as described here https://help.airbrake.io/kb/api-2/notifier-api-v3. Then a lot of code will gone.

This is a lot of work, but I feel that we have to do it. I will be glad to help you with this. Just let me know.