Rename core to runtime to reflect the teams name
Revert "Raise error when unbind fails on broker"

This reverts commit 3e64767e2b5d1d1860066abfc23aaee7e2132c97.
Revert "[finishes #56091544] service deprovision should give user an error when it fails"

This reverts commit 4c9093ce9618508beaae76dd4ec6fb72d42d6c9c.
remove delete_droplet from stagings controller

We are turning AppManager into an AppObserver that responds to changes made to an app.

This includes:
- sending the NATS messages (dea start/stop)
- kicking off staging
- cleaning it up from the blob store
rename AppManager to AppObserver
Extract out the stager and dea pool code
run bundle update. lockdown builder gem

also update activesupport to 3.2.x, otherwise
"bundle update" downgrades it.

locking down builder solves is of bundle update
failing to resolve dependencies.