Rename AppStager to AppManager
Add start app message to staging request
Accept the number of instances to start
Start the first indice when staging an app
Pass started instances in staging callback
Save droplet sha1 passed from stager response
Reset droplet sha and download uri in staging start request
Return started instances in staging callback
Mark app started in dea pool after staging
Choose stager with the app memory if app memory exceeds staging requirement
Convert app id to sym in dea pool as it comes in nats message