DB Actors should be using an appropriate Dispatcher

(Bug, To be Fixed , Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Internals
Summary: Right now, all Actors are using the standard Dispatcher. This is known to be bad; the MySQL-oriented ones should use a PinnedDispatcher instead.
This isn't causing problems yet, but will eventually start gumming up the system. We need to fix it before that happens.