Bump stemcell to 3112
Bump stemcell to 3112

Signed-off-by: Caroline Taymor <6220814f63f705589fa0394c3218bcae0c084690@pivotal.io>

pivotal-cf-experimental/ops-manager-example,pivotal-cf-experimental/ops-manager-example,pivotal-cf-experimental/ops-manager-example,pivotal-cf-experimental/ops-manager-example