Allow limiting DB bloat by excluding response from Activation record in some cases

Using a single db for many tenants that use web/blocking actions, we end up with:
* lots of Activation documents for blocking actions that are never used (on success, the response is consumed immediately, never looked up from db)
* lots of responses that vary in size, sometimes quite large (~1MB)

We plan to introduce a PR to:
* disable response storage for blocking+successful+not timed out (60s) Activation records
* introduce a ?debug param for action developers to use to force persistence of the response (even in case of blocking+successful+not timed Activations)
* introduce config flags to enable these response handling and debug options; default would be disabled

Need to investigate potential problems with sequence/composition usage (so scope of actions where response would be disabled, may include these as well).