First part of confd timer changes

This patch changes the resolution of the timers: the watcher timer
goes from 60s to 17s, and the polling-mode timer goes from 2 seconds
to 250ms. The code changes a bit more due to the changes in the units
of the various constants.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>