When a host port conflict is detected, kubelet should set the pod status to
fail. The failed status will then be polled by other components at a later time,
which allows replication controller to create a new pod if necessary.

To achieve this, this change stores the pod status information in a status map
upon the detecton of port conflict. GetPodStatus() consults this status map
before attempting to query docker. The entries in the status map will be removed
when the pod is no longer associated with the node.