* Add provider changes and tests
* Move config test fixtures
* Fix issue with explicit providing of envs_required=False for configuration from_*()
* Implement container API
* Increase priority of overriding from context
* Add docs and example
* Update changelog
* Update changelog
* Make prototype with enterpolation before parsing
* Add test for option.from_yaml() with missing env not required
* Make some cosmetic changes to _resolve_config_env_markers()
* Add test for option.from_ini() missing envs not required
* Skip schema test cause it requires internet connection
* Add tests for .from_yaml() for config and config option
* Add tests for .from_ini() for config and config option
* Add example for os.environ.setdefault() and envs interpolation
* Add/update docs on environment variables interpolation
* Update changelog
* Add implementation and basic test
* Add full test coverage + bugfix
* Add test coverage for .from_yaml() method
* Update setup.py, tox and dev requirements
* Stop running pydantic tests on Python 3.5 and below
* Remove pydantic from tox Python < 3.6
* Add example and docs
* Update features block
* Add extra test
* Update changelog
* Add bootstrap and remove created at from ghnav-flask app
* Update readme
* Add logo to the docs
* Update key features description
* Update README
* Change headers of API docs
* Add alabaster theme config
* Update docs index
* Add tutorials section
* Update what is DI page
* Update DI in Python page
* Update tutorials index page
* Update provider docs
* Update container docs
* Update examples docs