Provide Out Of Memory information in container status

Container processes can get killed by the kernel whenever they exceed their memory limit or when the overall memory available in the system is very low. When containers get killed by the kernel, there is no way to figure out if it died due to lack of memory.
To solve this problem, this patch modified docker to Identify out of memory kills inside containers and indicate that as part of the container status string. Since some containers can gracefully handle OOM kills, this patch does not attempt to bring down a container whenever an OOM occurs.

Ping @crosbymichael @vieux 
cc @bgrant0607
I propose separate method which means special Stop case. Also I prefer more and more methods than more and more fields in some god-structure which I need to intepret in one method(and this structure even in other package!). Also 98% that this future from which this will be proof will never happened.