2.0.0

Please note that this is a major version bump with breaking changes.

Changes in this release:

• Add support for the SRCF Goose authentication service.
• Add support for multiple signing keys.
• Return an error if the authentication responses is issued too far into the future from a local perspective.
• Improve compliance of the skew parameter with the WebAuth protocol.
• Raise an exception if RSA key file path and/or ID are not present.
• Improve documentation and example code.
• Bump internal dependencies.