Fastapi

* Add additional `responses` parameter to *path operation decorators* to extend responses in OpenAPI (and API docs).
* It also allows extending existing responses generated from `response_model`, declare other media types (like images), etc.
* The new documentation is here: <a href="https://fastapi.tiangolo.com/tutorial/additional-responses/" target="_blank">Additional Responses</a>.
* `responses` can also be added to `.include_router()`, the updated docs are here: <a href="https://fastapi.tiangolo.com/tutorial/bigger-applications/#add-some-custom-tags-and-responses" target="_blank">Bigger Applications</a>.
* PR <a href="https://github.com/tiangolo/fastapi/pull/97" target="_blank">#97</a> originally initiated by <a href="https://github.com/barsi" target="_blank">barsi</a>.

* Update `scripts/test-cov-html.sh` to allow passing extra parameters like `-vv`, for development.

* Add `auto_error` parameter to security utility functions. Allowing them to be optional. Also allowing to have multiple alternative security schemes that are then checked in a single dependency instead of each one verifying and returning the error to the client automatically when not satisfied. PR <a href="https://github.com/tiangolo/fastapi/pull/134" target="_blank">#134</a>.

* Update <a href="https://fastapi.tiangolo.com/tutorial/sql-databases/#create-a-middleware-to-handle-sessions" target="_blank">SQL Tutorial</a> to close database sessions even when there are exceptions. PR <a href="https://github.com/tiangolo/fastapi/pull/89" target="_blank">#89</a> by <a href="https://github.com/alexiri" target="_blank">alexiri</a>.

* Fix duplicate dependency in `pyproject.toml`. PR <a href="https://github.com/tiangolo/fastapi/pull/128" target="_blank">#128</a> by <a href="https://github.com/zxalif" target="_blank">zxalif</a>.

* Add Gitter chat, badge, links, etc. <a href="https://gitter.im/tiangolo/fastapi" target="_blank">https://gitter.im/tiangolo/fastapi
</a>. PR <a href="https://github.com/tiangolo/fastapi/pull/117" target="_blank">#117</a>.

* Add docs about <a href="https://fastapi.tiangolo.com/tutorial/extending-openapi/" target="_blank">Extending OpenAPI</a>. PR <a href="https://github.com/tiangolo/fastapi/pull/126" target="_blank">#126</a>.

* Make Travis run Ubuntu Xenial (newer version) and Python 3.7 instead of Python 3.7-dev. PR <a href="https://github.com/tiangolo/fastapi/pull/92" target="_blank">#92</a> by <a href="https://github.com/blueyed" target="_blank">blueyed</a>.

* Fix duplicated param variable creation. PR <a href="https://github.com/tiangolo/fastapi/pull/123" target="_blank">#123</a> by <a href="https://github.com/yihuang" target="_blank">yihuang</a>.

* Add note in <a href="https://fastapi.tiangolo.com/tutorial/response-model/" target="_blank">Response Model docs</a> about why using a function parameter instead of a function return type annotation. PR <a href="https://github.com/tiangolo/fastapi/pull/109" target="_blank">#109</a> by <a href="https://github.com/JHSaunders" target="_blank">JHSaunders</a>.

* Fix event docs (startup/shutdown) function name. PR <a href="https://github.com/tiangolo/fastapi/pull/105" target="_blank">#105</a> by <a href="https://github.com/stratosgear" target="_blank">stratosgear</a>.

* Fix OpenAPI (JSON Schema) for declarations of Python `Union` (JSON Schema `additionalProperties`). PR <a href="https://github.com/tiangolo/fastapi/pull/121" target="_blank">#121</a>.

* Update <a href="https://fastapi.tiangolo.com/tutorial/background-tasks/" target="_blank">Background Tasks</a> with a note on Celery.

* Document response models using unions and lists, updated at: <a href="https://fastapi.tiangolo.com/tutorial/extra-models/" target="_blank">Extra Models</a>. PR <a href="https://github.com/tiangolo/fastapi/pull/108" target="_blank">#108</a>.

* Add docs and tests for <a href="https://github.com/encode/databases" target="_blank">encode/databases</a>. New docs at: <a href="https://fastapi.tiangolo.com/tutorial/async-sql-databases/" target="_blank">Async SQL (Relational) Databases</a>. PR <a href="https://github.com/tiangolo/fastapi/pull/107" target="_blank">#107</a>.

* Add support for Background Tasks in *path operation functions* and dependencies. New documentation about <a href="https://fastapi.tiangolo.com/tutorial/background-tasks/" target="_blank">Background Tasks is here</a>. PR <a href="https://github.com/tiangolo/fastapi/pull/103" target="_blank">#103</a>.

* Add support for `.websocket_route()` in `APIRouter`. PR <a href="https://github.com/tiangolo/fastapi/pull/100" target="_blank">#100</a> by <a href="https://github.com/euri10" target="_blank">euri10</a>.

* New docs section about <a href="https://fastapi.tiangolo.com/tutorial/events/" target="_blank">Events: startup - shutdown</a>. PR <a href="https://github.com/tiangolo/fastapi/pull/99" target="_blank">#99</a>.