Provide support for other storage engines

[hschne]

Consider using the Kredis library, and possibly AllFutures to create a model-like persistence (more on this in a moment). One nice side-effect of using Redis is that you can rely on the key eviction policy to remove the oldest data, no need for a cleanup task.

Originally posted by @leastbad in https://github.com/hschne/rails-mini-profiler/issues/55#issuecomment-910037302