Fixed bug where same header was being added multiple times

Update dependencies and target frameworks

Added support for URI escaping the (request-target) header

Added HMAC signing algorithm.

Changed ISigningAlgorithm interface to take a byte array instead.

Fixed a few bugs:

- Signature failed to parse due to quoting of UNIX timestamps
- Digest calculation failed due to WCF modifying the Message

Fixed key-id generation bug

Fixed Signature header bug

Split WCF parts into separate project, remove obsolete methods

Consolidate configuration between WCF and HttpClient

Add support for HttpClient, conditionally include Digest