Marconi's API aims to be as flexible as possible without sacrificing safety, consistency nor availability. Shards introduced the ability to have separate clusters for queues which helps with scaling Marconi horizontally. This process has to be done manually by the system administrator and it's just related to queue's distribution and not specifically to the storage capabilities.
Queue flavors aim to add a way for selecting dynamically which store to use for a specific queue based on the storage capabilities. For instance, it would be possible to create an `in-memory` queue or a `blob` queue, etc.
This would allow the user to have some control over the tradeoffs inherent in the backing store, e.g., do I want a queue that is fast but less durable (e.g., for piping lots of little notification messages - think UDP), or do I want something that is a little slower but offers more guarantees (e.g., for critical metering/billable events - think TCP)?
