Fidelius

Fixed

- Typo in `vault` optional-dependencies (`havc` -> `hvac`)

Changed

- Pip installation now requires you to specify optional dependencies with either
`pip install fidelius[aws]` for AWS Parameter Store support,
`pip install fidelius[vault]` for Hashicorp Vault support or
`pip install fidelius[aws,vault]` for both.

Added

- Hashicorp Vault integration

Added

- An interface for Fidelius gateway repos and admins to fulfil
- A mock implementation of a Fidelius gateway repo and admin that use a
simple singleton dict to store (and share) data during runtime
- Unittests for the mock implementation
- Unittests for the Parameter Store implementation using LocalStack
- A Factory class to get different implementation classes
- Methods to delete parameters
- Config params for the `AwsParamStoreRepo` to use a custom AWS endpoint in
order to hook up to stuff like LocalStack for testing and such

Changed

- The API a little bit so we're no longer backwards compatible (hence the
major version bump to 1.0.0)
- All config params can now be explicitly given to the `AwsParamStoreRepo`
in addition to being picked up from environment variables if not supplied

Changed

- Just a version number bump because 0.5.0 was yanked temporarily while
dealing with code dependent on certain internal default values in fidelius
0.4.0 that were removed

Changed

- The version and created a new release to trigger the CI/CD thingamajig!