Changelog

Unreleased Changes

The cryptography library used is now configurable.
- By default ring is used (the use_ring feature).
- You can use the use_openssl feature to use openssl instead
  - e.g. in your Cargo.toml:
```
[dependencies.hawk]
version = "..."
features = ["use_openssl"]
default-features = false
```
- You can use neither and provide your own implementation using the functions in hawk::crypto if neither feature is enabled.
- Note that enabling both use_ring and use_openssl will cause a build failure.
BREAKING: Many functions that previously returned T now return hawk::Result<T>.
- Specifically, PayloadHasher::{hash,update,finish}, Key::{new,sign}.
BREAKING: hawk::SHA{256,384,512} are now const DigestAlgorithms and not aliases for ring::Algorithm
BREAKING: Key::new now takes a DigestAlgorithm and not a &'static ring::Algorithm.
- If you were passing e.g. &hawk::SHA256, you probably just need to pass hawk::SHA256 now instead.
BREAKING (though unlikely): Error::Rng has been removed, and Error::Crypto added