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.
That is actually what ends up happening in the Error class. If there is an exception context, `errtype` gets overwritten [here](https://github.com/airbrake/airbrake-python/pull/8/files#discussion_r14509388)

Since that's definitely not obvious, I'll move that logic into this function.