ControlledDynamicWebAppCluster: support rebind

- Use attributes rather than fields for holding refs to children
Fix RabbitBroker
Fix Jboss7ServerRebindIntegrationTest
Fix AbstractGeoDnsServiceImpl

- support if setTargetEntityProvider called after entity is managed
- allow targetEntityProvider to be set in flags/config
Fix rest's ApplicationResourceIntegrationTest
Fix CliIntegrationTest (path to brooklyn script)