clean up agent directories after killing agents in integration tests

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
stop using fakes in dummy platform

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
introduce dummy job supervisor and -M command line option

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
fix go-smtpd submodule to use https

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>