A model to represent the locality information of an application. The locality information refers to the
 whereabouts of the physical execution of a samza container. This locality information is used
 to place the container, if possible, on the same host that it was last seen. By doing this, stateful applications
 can minimize the bootstrap time of their state by leveraging the local copy.
 It is suffice to have only 
ProcessorLocality model and use it within locality manager. However, this abstraction
 enables us extend locality beyond container. e.g. It is useful to track task locality to enable heterogeneous containers
 or fine grained execution model.
 In YARN deployment model, processors are interchangeably used for container and 
processorIdrefers to
 logical container id.