terminology change: user "retry" instead of "waiting"

Use "retry" in queue/exchange naming instead of "waiting".

add more elaborate next-ttl reference implementation

v1.0.1

bump up version

fixed exponential backoff

v1.0.0

new version for fixed exponential backoff

exponential back off implementation

Implementation for exponential back off and finally tests are added as well.

queue config abilities added.

You can configure the dead letter queues and the waiting queue.

mesage acknoledgement added

Carrot acknowledges every message even if it fails, since it sends the message to the waiting queue any way.

Initial usable version

Supports simple delayed retry and exception handling.