1) Introduce new managers - ProjectManager and DomainManager. Moved all domain related code from AccountManager to DomainManager.
2) Moved some code from ManagementServerImpl to the correct managers.
3) New resource limit for Domain - Project
* 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.
