1) introduced a global configuration variable job.cancel.threshold.minutes
2) Default value for the job.cancel.threshold.minutes is 60 minutes, if a job has been staying in processing state for over 60 minutes, system will forcely remove it from the queue to allow others to run
* Implement callCreate() and execute() methods in apis extending BaseAsyncCreateCmd (example - CreateVolumeCmd)
* Implement execute() method in apis extending BaseCmd and BaseAsyncCmd (example - deleteVolumeCmd and deleteUserCmd)
We no longer need createMethod(), method(), manager() fields in @Implementation annotation, cleanup has to be done.
2) Moved Account/User related methods to AccountManagerImpl. Methods are exposed via AccountService interface.
3) Enhanced exception handing for Api calls.
4) Created ConfigurationService interface, all Api config methods are exposed via it.
