[Reviewer: Andy][From: Alex] Get useful diags when chronos hangs and is restarted by monit

This enhances the chronos infrastructure to dump out some useful diags when chronos hangs (and help with debugging issues like #18, #20 and #40)

It also changes the recovery mechanism when chronos hangs so that chronos is aborted and restarted in separate monit cycles, rather than being restarted in a single cycle, the aim being to avoid race conditions if chronos doesn't restart promptly. Note that this is the same way that monit restarts a hung sprout. 
Monit follows up this script with `/etc/init.d/chronos abort`, which dumps a core and triggers the diags collection.