Implemented basic per-feature state storage and feature lookup
Feature encode/decode now works, a bit of cleanup

Signed-off-by: zml2008 <zach@zachsthings.com>
Added returnsPayload option,
which if set to true passes the FloodgateMessage payload to the next handler instead of the
FloodgateMessage itself

Signed-off-by: zml2008 <zach@zachsthings.com>
Sketch out testing framework
Contine work on improved testing system, stub out GuarantiesDeliveryFeature a bit more

Signed-off-by: zml2008 <zach@zachsthings.com>