Set delay in seconds rather than microseconds

It doesn't make a lot of sense to set the delay in microseconds,
especially since the maximum run time is set in seconds. The main reason
why we use microseconds is really just because that's what usleep wants,
and that's just an implementation detail.

Let the delays be specified in seconds instead so that we use the same
time unit for all configure options.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>