CCAR:
1- add mode member to MachineParameters. This string member can be "start" or "get" or "getorstart"
if mode=="start" a new container is launched on each request.
if mode=="get" an old container with the requested parameters is used if it exists.
if mode=="getorstart" an old container is used or a new one if the old one does not exist.
2- add policy member to MachineParameters. This string member replaces the enum policy argument
of GiveContainer and StartContainer. This argument is left for compatibility but will be removed soon.
3- replace LoadRateManager methods by three objects. These objects are referenced in a map (_resourceManagerMap)
that can be extended without changing IDL interface.
4- add a Find method to ResourceManager IDL for testing purpose.
