Add generate-manifest script from master
Add generate-manifest script from master

Signed-off-by: Tiago Scolari <f438736fd7dd1cb07f8d2a37f4499d0a0272a752@pivotal.io>

pivotal-cf/cf-rabbitmq-release,pivotal-cf/cf-rabbitmq-release,pivotal-cf/cf-rabbitmq-release,pivotal-cf/cf-rabbitmq-release