started working on health monitor daemon
added a main loop to HealthMonitor; added report class

Also, add logging to health monitor.

Still need to implement the actual monitoring of instances :-)
add smtp server and account credentials to health monitor config
workaround for bug in IOUtil.closeQuietly

I guess this is why you shouldn't reinvent the wheel. Sigh.
more progress on health monitor: almost working

Changed the Health servlet so that there is a proper model
object to represent webapp instance health, convertable
to/from JSON.

Implemented the actual checking and status reporting
in HealthMonitor.

Added a TestMain to allow testing.

Current failure mode is that it reports that there are no
builder threads (even though the actual instances being
checked to report having a positive number of connected
builder threads.)  Need to investigate.
Fix stupid cut and paste error
health monitor appears to be completely working!

The only problem was the issue deserializing the HealthData
object returned by the instances (which was fixed in the
previous commit.)
send email when unhealthy instances are detected
add timestamps to report entries
report when instance statuses change

Also report unhealthy instances if the last report was
sufficiently long in the past (currently defaults to 2 hours.)

Things seem to be in pretty good shape. Next step is
packaging it for deployment.
allow configuration of health monitor

Also, refactored feature configuration into a hash rather
than using separate variables.
this should not be here
build and package the health monitor for deployment