SLING-2566 - installer core deactivate() interrupts background thread, WDYT?

[Bertrand Delacretaz]

Hi (mostly Carsten I guess),

See patch attached to SLING-2566 - I think it makes sense for the
installer, when deactivated, to make sure its background thread exits
quickly.

I haven't committed the patch yet.

WDYT?

-Bertrand