Use gc_thresh1 set in stemcell in nats job

Signed-off-by: Maria Shaldibina <mshaldibina@pivotal.io>
Remove system_rescan_scsi_bus stage

It was only used by ruby agent

Signed-off-by: Maria Shaldibina <mshaldibina@pivotal.io>
Bump logging gem to 1.8.2

Signed-off-by: Maria Shaldibina <mshaldibina@pivotal.io>
Fix leaking fds in task helper

Signed-off-by: Maria Shaldibina <mshaldibina@pivotal.io>