Raygun4py

Breaking changes:
- Support for Python 2.7 has been dropped

Bug Fixes:
- Removes largest local/global variables in crash payload to ensure payload size limit is not breached (optional)
- We now provide `enforce_payload_size_limit` and `log_payload_size_limit_breaches` as configuration options, both enabled by default
- These control whether the provider will attempt to remove variables if there is an oversized payload and log which variables were removed

Features:
- Added `RaygunHandler.from_sender()` factory to construct a `RaygunHandler` instance using an existing `RaygunSender`. This allows for additional configuration of the sender.
- Added a `config` parameter the to Flask and WSGI middleware provider constructors. This also allows for additional configuration of the sender.
- The `RaygunHandler` now adds tags corresponding to the logging level, which now defaults to `logging.ERROR`.
- Errors/exceptions sent via the `RaygunHandler` now have their message overriden by the logged message.
Bug fixes:
- The `RaygunHandler` now attempts to capture `exc_info` from the `record`. This can be obtained if `logger.exception()` is used or if `exc_info=True` is set in the logger call.
- If `exc_info` cannot be obtained by the `RaygunHandler`, it no longer attempts to construct a `RaygunErrorMessage` with `None` values. Instead, it generates a fallback error message using information gathered from the `record`. This is essentially an error with a single stack frame representing the call to the logger.
Quality of life updates:
- Updated `CONTRIBUTING.MD`.
- Got unit tests running again (`django` upgrade).
- Updated `python3/samples/sample.py` and `python3/samples/sampleWithLogging.py`.
- Cleaned up `python3/raygun4py/cli.py`.

Features:
- Added a new config option, `transmit_environment_variables`, to control sending any environment variables at all
- Added support to `filter_keys` config option for ignoring keys with a simple wildcard approach. See README for more information

Bugfixes
- Add request `rawData` to the `build_wsgi_compliant_request` utilities to fix a bug where `rawData` is set manually then overwritten by an empty object.

Bugfixes
- Fix `set_request_details` builder method not returning self causing it to be unchainable

Bugfixes
- Set version correctly in crash report sent to Raygun API ([78](https://github.com/MindscapeHQ/raygun4py/pull/79))

- Improve Flash middleware ([79](https://github.com/MindscapeHQ/raygun4py/pull/79))

Thanks to brock for both of these changes