Responses

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- Fixed invalid README formatted.
- Fixed string formatting in error message.

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- Added Python 3.8 support
- Remove Python 3.4 from test suite matrix.
- The `response.request` object now has a `params` attribute that contains the query string parameters from the request that was captured.
- `add_passthru` now supports `re` pattern objects to match URLs.
- ConnectionErrors raised by responses now include more details on the request that was attempted and the mocks registered.

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- Fixed regression with `add_callback()` and content-type header.
- Fixed implicit dependency on urllib3>1.23.0

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- Fixed cookie parsing and enabled multiple cookies to be set by using a list of
tuple values.

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- Added pypi badges to README.
- Fixed formatting issues in README.
- Quoted cookie values are returned correctly now.
- Improved compatibility for pytest 5
- Module level method names are no longer generated dynamically improving IDE navigation.

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- Improved documentation.
- Improved installation requirements for py3
- ConnectionError's raised by responses now indicate which request
path/method failed to match a mock.
- `test_responses.py` is no longer part of the installation targets.