This is 0.24

Added changelog entry for 0.23

This is 0.22

Added changelog entry and bumped to 0.21

This is 0.20

Added changelog entry

Allow header to remain JSON even if someone changes the payload seria…

…lizer

Fixed a bug that caused with custom digest methods and hmac key deriv…

…ation.

This is 0.16

This is 0.15