Added a wait-for-activation option to shared-store master HA policies.
This option is enabled by default to ensure unchanged server startup behavior.
If this option is enabled, ActiveMQServer.start() with a shared-store master server will not return
before the server has been activated.
If this options is disabled, start() will return after a background activation thread has been started.
The caller can use waitForActivation() to wait until server is activated, or just check the current activation status.
(cherry picked from commit 6017e305d90664b4bf5b8f891e43514907df9a4b)
(cherry picked from commit 7aa50546b3dc6c012bd7d4118d82055ffd1e1226)
88e629a7ae
