Add explicit reiteration delay to object selector

[vdomnich-yadro]

To prevent object selector from excessive re-iteration over bolt database we make a small delay after we made a pass over the database and before we start a new cycle.

Currently this delay is calculated based on Age of objects in the selector's filter. However, Age filter is quite specific and is used just for deletion. More flexible approach would be to have reiterateDelay that can be explicitly supplied into object selector.