Built-in caching in nosqlprotocol

As nosqlprotocol is the first module in the routing chain, the regular cache filter will be of value. However, not as much as one would expect, as, since the cache stores result sets, nosqlprotocol would at every cache hit still have to perform the JSON->BSON conversion, which is a heavy operation.

If instead the nosqlprotocol would have its own cache that stores BSON data, then a cache hit would require no processing but the data could simply be sent to the client.