wait for seconds only checked for positivity

[Heliosmaster]

https://github.com/rill-event-sourcing/rill/blob/master/rill-psql/src/rill/event_store/psql.clj#L154

Here the value of wait for seconds is not used, only checked for positivity. If using Thread/sleep we should call it wait-for-milliseconds (for consistency), and even if that is negative we should always have a timeout like we do now of 200 milliseconds, otherwise you really overload the server.