Changes since 2.0.0-beta.1

Summary of changes since 1.0.0

Raise minimum supported Rust version (MSRV) to 1.45.
Upgrade reqwest to 0.11 and rename feature flag to reqwest. This upgrades tokio to 1.0 and removes support for both the reqwest-010 and reqwest-09 feature flags.
Drop support for futures 0.1 and remove the futures-01 and futures-03 feature flags; only async/await and futures 0.3 are now supported (without requiring any feature flags).
Eliminate Async* traits and move the request_async methods to the underlying *Request structs
Rename set_redirect_url to set_redirect_uri (see #39 for context).
Migrate public API from http 0.1 to 0.2.
Return error types that implement std::error::Error instead of failure::Fail.
Expose serde_path_to_error::Error<serde_json::Error>> in several error types to make JSON deserialization errors easier to diagnose.
Add #[non_exhaustive] attribute to AuthType to support non-breaking additions in the future.
Have Client::user_info fail fast with a new ConfigurationError enum when the relevant OAuth2 endpoint hasn't been configured from the OpenID Connect Discovery metadata. Previously, an error would not be returned until a call to request/request_async.

Have reqwest client use rustls-tls by default instead of native TLS. This behavior can be overridden using the native-tls feature flag.
Disable deprecated OpenID Connect conformance tests.