Require minimum bosh release version 261 for sha2
Require minimum bosh release version 261 for sha2

[finishes #148251403]

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

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release